KR20210096237A - A grain-oriented electrical steel sheet, a method for manufacturing a grain-oriented electrical steel sheet, and an annealing separator used for manufacturing a grain-oriented electrical steel sheet - Google Patents

Abstract

A grain-oriented electrical steel sheet having excellent magnetic properties and excellent adhesion of a primary coating to a steel sheet is provided. A base steel sheet having a predetermined chemical composition, and _{a primary film formed on the surface of the base steel sheet and containing Mg 2} SiO ₄ as a main component, the glow in the thickness direction of the grain-oriented electrical steel sheet from the surface of the primary film The peak position of the Al emission intensity obtained when elemental analysis by the discharge emission spectrometry method is performed is arranged within the range of 2.4 to 12.0 µm in the plate thickness direction from the surface of the primary film, and Al oxide at the peak position of the Al emission intensity , and the number density of the Al oxides of 0.2 µm or more is 0.03 to 0.18 pieces/µm ² in terms of an area-based equivalent circle diameter, and a plurality of Als in the observation area of 30 µm×50 µm at the peak position of the Al emission intensity. Among the oxides, the total cross-sectional area of specific Al oxides having a cross-sectional area of 0.4 to 10.0 µm ² is 75.0% or more of the total cross-sectional area of all Al oxides in the observation region.

Description

A grain-oriented electrical steel sheet, a method for manufacturing a grain-oriented electrical steel sheet, and an annealing separator used for manufacturing a grain-oriented electrical steel sheet

The present invention relates to a grain-oriented electrical steel sheet, a method for manufacturing a grain-oriented electrical steel sheet, and an annealing separator used for manufacturing a grain-oriented electrical steel sheet.

The grain-oriented electrical steel sheet is a steel sheet in which Si is contained in a mass % of about 0.5 to 7% and the crystal orientation is integrated in a {110}<001> orientation (Goss orientation). A catatropic grain growth phenomenon called secondary recrystallization is used to control the crystal orientation.

The manufacturing method of the grain-oriented electrical steel sheet is as follows. The slab is heated and hot-rolled to manufacture a hot-rolled steel sheet. A hot-rolled steel sheet is annealed as needed. Pickling the hot-rolled steel sheet. With respect to the hot-rolled steel sheet after pickling, it cold-rolls at 80% or more of cold rolling ratio, and manufactures a cold-rolled steel sheet. The cold-rolled steel sheet is subjected to decarburization annealing to exhibit primary recrystallization. Finish annealing is performed on the cold rolled steel sheet after decarburization annealing to exhibit secondary recrystallization. Through the above process, a grain-oriented electrical steel sheet is manufactured.

After the decarburization annealing described above and before the finish annealing, an aqueous slurry containing an annealing separator containing MgO as a main component is applied on the surface of the cold-rolled steel sheet and dried. After the cold-rolled steel sheet dried by the annealing separator is wound around a coil, finish annealing is performed. _{In the final annealing, MgO in the annealing separator and SiO 2} in the internal oxide layer formed on the surface of the cold-rolled steel sheet during decarburization annealing react to form a primary film containing forsterite (Mg ₂ SiO ₄ ) as a main component on the surface is formed in After forming the primary film, an insulating film (also referred to as a secondary film) containing, for example, colloidal silica and phosphate is formed on the primary film. The primary film and the insulating film have a smaller coefficient of thermal expansion than that of the steel sheet. Therefore, the primary film, together with the insulating film, provides tension to the steel sheet to reduce iron loss. The primary coating also enhances the adhesion of the insulating coating to the steel sheet. Therefore, it is preferable that the adhesiveness to the steel plate of a primary film is high.

On the other hand, it is also effective to reduce the hysteresis loss by increasing the magnetic flux density to reduce the iron loss of the grain-oriented electrical steel sheet.

In order to increase the magnetic flux density of the grain-oriented electrical steel sheet, it is effective to integrate the crystal orientation of the mother steel sheet into the Goss orientation. A technique for increasing the integration in the Goss direction is proposed in Patent Documents 1 to 3. In these patent documents, a magnetic property improving element (Sn, Sb, Bi, Te, Pb, Se, etc.) which enhances the action of the inhibitor is contained in the steel sheet. Thereby, the integration in the Goss direction is increased, and the magnetic flux density can be increased.

However, when a magnetic property improving element is contained, a part of the primary film aggregates, and the interface between the steel sheet and the primary film tends to be flattened. In this case, the adhesiveness to the steel plate of a primary film falls.

Patent Documents 4, 5, 6 and 7 disclose techniques for increasing the adhesion of the primary coating to the steel sheet.

In Patent Document 4, the slab contains Ce in an amount of 0.001 to 0.1%, and a primary film containing ^{0.01 to 1000 mg/m 2 of Ce is formed on the surface of the steel sheet.} In Patent Document 5, in a grain-oriented electrical steel sheet containing Si: 1.8 to 7% and having a primary film mainly composed of forsterite on the surface, Ce in the primary film is 0.001 to 1000 mg per side as a weight per unit area in the primary film. /m ² contained.

In Patent Document 6, in an annealing separator containing MgO as a main component, 0.1 to 10% of a rare earth metal compound, 0.1 to 10% of at least one alkaline earth metal compound selected from Ca, Sr, or Ba, and 0.01 to a sulfur compound By containing the compound containing 5% to 5%, a primary coating characterized by containing at least one alkaline earth metal compound selected from Ca, Sr or Ba and a rare earth element in the primary coating is formed.

In Patent Document 7, a primary coating comprising at least one element selected from Ca, Sr or Ba, 0.1 to 1.0% of a rare earth metal element compound, and a compound containing sulfur is formed.

Japanese Patent Laid-Open No. 6-88171 Japanese Patent Laid-Open No. 8-269552 Japanese Patent Laid-Open No. 2005-290446 Japanese Patent Laid-Open No. 2008-127634 Japanese Patent Laid-Open No. 2012-214902 International Publication No. 2008/062853 Japanese Patent Laid-Open No. 2009-270129

However, when the annealing separator contains a rare earth element compound such as Y, La or Ce, and a primary film containing Y, La, or Ce is formed, magnetic properties may be deteriorated. In addition, if the number density of particles in the raw material powder of rare earth element compounds such as Y, La, Ce, etc. or additives such as Ca, Sr, Ba is insufficient when adjusting the annealing separator, a region where the primary coating is insufficiently developed occurs. and adhesiveness may fall. In addition, although the grain-oriented electrical steel sheet may be required to have rust resistance, Patent Documents 1 to 4 do not contain any description regarding rust resistance.

An object of the present invention is to provide a grain-oriented electrical steel sheet having excellent magnetic properties, excellent adhesion to a mother steel sheet of the primary coating, and excellent rust resistance, a method for manufacturing a grain-oriented electrical steel sheet, and a grain-oriented electrical steel sheet used for manufacturing a grain-oriented electrical steel sheet To provide an annealing separator.

The grain-oriented electrical steel sheet according to the present invention contains, in mass%, C: 0.005% or less, Si: 2.5 to 4.5%, Mn: 0.02 to 0.2%, and at least one element selected from the group consisting of S and Se: 0.005 in total. % or less, sol. Al: 0.01% or less, and N: 0.01% or less, the balance being formed on the surface of a base steel sheet having a chemical composition containing Fe and impurities, and containing Mg ₂ SiO ₄ as a main component The peak position of the Al emission intensity obtained when the primary coating is provided and elemental analysis is performed by the glow discharge emission spectrometry method in the sheet thickness direction of the grain-oriented electrical steel sheet from the surface of the primary coating is from the surface of the primary coating to the plate thickness It is disposed within the range of 2.4 to 12.0 μm in the direction, and is an Al oxide at the peak position of the Al emission intensity, and the number density of the Al oxide of 0.2 μm or more is 0.03 to 0.18/μm ² in terms of an area-based equivalent circle diameter. ^{, The total cross-sectional area of a specific Al oxide having a cross-sectional area of 0.4 to 10.0 µm 2} among a plurality of Al oxides in an observation region of 30 µm×50 µm at the peak position of the Al emission intensity is the total cross-sectional area of all Al oxides in the observation region of 75.0% or more.

The method for manufacturing a grain-oriented electrical steel sheet according to the present invention comprises, in mass%, C: 0.1% or less, Si: 2.5 to 4.5%, Mn: 0.02 to 0.2%, and at least one element selected from the group consisting of S and Se: 0.005 to 0.07% in total, sol. Al: 0.005 to 0.05%, and N: 0.001 to 0.030%, the balance is subjected to cold rolling at a cold rolling rate of 80% or more with respect to a hot-rolled steel sheet containing Fe and impurities to produce a cold-rolled steel sheet serving as a base steel sheet The step of performing decarburization annealing on the cold rolled steel sheet, and applying an aqueous slurry containing an annealing separator to the surface of the cold rolled steel sheet after decarburization annealing, and an aqueous slurry on the surface of the cold rolled steel sheet in a furnace at 400 to 1000°C It is provided with the process of drying and the process of performing finish annealing with respect to the cold-rolled steel sheet after the aqueous slurry has dried. The annealing separator includes MgO and at least one compound of a metal selected from the group consisting of Y, La, and Ce, and at least one compound of a metal selected from the group consisting of Ti, Zr, and Hf; It contains at least one metal compound selected from the group consisting of Ca, Sr, and Ba, and when the MgO content in the annealing separator is 100% by mass%, selected from the group consisting of Y, La, and Ce The total oxide content of the compound to be used is 0.8 to 8.0%, and the total oxide content of the metal compound selected from the group consisting of Ti, Zr, and Hf is 0.5 to 9.0%, and the Ca, Sr, Ba The total content in terms of sulfate of the metal compound selected from the group consisting of is 0.5 to 8.0%, the average particle diameter of the metal compound selected from the group consisting of Ca, Sr, and Ba is 12 µm or less, and the Ca, Sr, The ratio of the average particle diameter of the compound of the metal selected from the group consisting of Ba to the average particle diameter of the compound of the metal selected from the group consisting of Y, La, and Ce is 0.1 to 3.0, and in the group consisting of Y, La, and Ce The sum of the total content of the selected metal compound in terms of oxide and the total content of the compound of the metal selected from the group consisting of Ti, Zr, and Hf in terms of oxide is 2.0 to 12.5%, which is contained in the annealing separator The ratio of the total number of Y, La and Ce atoms to the total number of Ti, Zr, and Hf atoms is 0.18 to 4.0, and is particles of a metal compound selected from the group consisting of Y, La, and Ce, It is a compound of a metal selected from the group consisting of Ti, Zr, and Hf, wherein the number density of 0.1 μm or more in terms of the equivalent sphere diameter on a volume basis is 2 billion pieces/g or more, and the particle size of the particles of 0.1 μm or more in the equivalent sphere diameter on a volume basis. The number density is 2 billion pieces/g or more, and it consists of Ca, Sr, and Ba. It is a compound of a metal selected from the group, and the number density of particles of 0.1 μm or more in terms of volume-based equivalent sphere diameter is 2 billion particles/g or more.

The annealing separator used for manufacturing a grain-oriented electrical steel sheet according to the present invention comprises at least one compound of a metal selected from the group consisting of MgO, Y, La, and Ce, and Ti, Zr, and Hf from the group consisting of When at least one compound of the selected metal and at least one compound of a metal selected from the group consisting of Ca, Sr, and Ba are contained, and the MgO content in the annealing separator is 100% by mass% , Y, La, Ce, the total oxide content of the compound selected from the group consisting of 0.8 to 8.0%, the total oxide content of the compound of the metal selected from the group consisting of Ti, Zr, and Hf is 0.5 to 9.0%, and the total content in terms of sulfate of the metal compound selected from the group consisting of Ca, Sr, and Ba is 0.5 to 8.0%. The average particle diameter of the compound of the metal selected from the group consisting of Ca, Sr, and Ba is 12 μm or less, and the average particle diameter of the compound of the metal selected from the group consisting of Ca, Sr, and Ba is Y, La, Ce. The ratio to the average particle diameter of the compound of a metal selected from the group consisting of 0.1 to 3.0, the total content of the compound of the metal selected from the group consisting of Y, La, and Ce in terms of oxide and the group consisting of Ti, Zr, and Hf The sum total of the said sum total content of the said oxide conversion of the metal compound selected from is 2.0 to 12.5%. A ratio of the total number of Y, La, and Ce atoms to the total number of Ti, Zr, and Hf atoms contained in the annealing separator is 0.18 to 4.0, and a metal selected from the group consisting of Y, La, and Ce. is a particle of a compound of the present invention, the number density of particles of 0.1 μm or more with a sphere-equivalent diameter on a volume basis is 2 billion pieces/g or more, and is a particle of a metal compound selected from the group consisting of Ti, Zr, and Hf, and is a particle of a metal compound of the volume basis The number density of particles of 0.1 μm or more in terms of the equivalent sphere diameter of The number density of the above-mentioned particles is 2 billion pieces/g or more.

The grain-oriented electrical steel sheet according to the present invention has excellent magnetic properties and excellent adhesion of the primary coating to the base steel sheet. The manufacturing method according to the present invention can manufacture the grain-oriented electrical steel sheet described above. The annealing separator according to the present invention is applied to the above manufacturing method, whereby a grain-oriented electrical steel sheet can be manufactured.

The present inventors investigated and investigated the magnetic properties of a grain-oriented electrical steel sheet containing a magnetic property improving element and the adhesiveness of a primary film formed by containing a Y compound, a La compound and a Ce compound in an annealing separator. As a result, the present inventors acquired the following knowledge.

The interface between the primary film of the grain-oriented electrical steel sheet and the steel sheet has a fitting structure. Specifically, in the vicinity of the interface between the primary film and the steel sheet, the root of the primary film is surrounded inside the steel sheet. As the root of the primary film enters the inside of the steel sheet, the adhesion of the primary film to the steel sheet increases. In addition, the more the roots of the primary coating are dispersed inside the steel sheet (the more they are surrounded), the higher the adhesion of the primary coating to the steel sheet is.

On the other hand, if the root of the primary film enters too deeply into the steel sheet, the root of the primary film prevents secondary recrystallization of the Goss orientation. Therefore, crystal grains of random orientation increase in the surface layer. In addition, the root of the primary coating becomes an inhibitory factor of the magnetic domain wall movement, and the magnetic properties deteriorate. Similarly, when the roots of the primary coating are excessively dispersed inside the steel sheet, the roots of the primary coating interfere with secondary recrystallization in the Goss orientation, so that grains of random orientation increase in the surface layer. In addition, the root of the primary coating becomes an inhibitory factor of the magnetic domain wall movement, and the magnetic properties deteriorate.

Based on the above findings, the present inventors also investigated the state of the root of the primary coating, the magnetic properties of the grain-oriented electrical steel sheet, and the adhesion of the primary coating.

When the primary film is formed by containing the Y, La, Ce compound in the annealing separator, as described above, the magnetic properties are lowered. This is considered to be because the root of the primary coating enters too deeply into the inside of the steel sheet and inhibits the movement of the magnetic domain wall.

Therefore, the present inventors tried to form a primary film by lowering the content of Y, La, and Ce compounds in the annealing separator mainly composed of MgO and containing Ti, Zr, and Hf compounds as a substitute. , attempted to increase the density in the annealing separator (raw material powder) before adjusting the number density of particles of the compound to an aqueous slurry. As a result, it was found that the magnetic properties of the grain-oriented electrical steel sheet were improved, and the adhesion of the primary coating film was also improved in some cases.

The present inventors obtained the following knowledge as a result of further examining the Y, La, Ce compound and Ti, Zr, and Hf compound in the annealing separator. Since unreacted Y, La, Ce compounds and Ti, Zr, and Hf compounds are difficult to form a primary film, the primary film does not become dense. In this case, the primary film cannot cover the entire surface of the steel sheet, and a part of the surface of the steel sheet is exposed. When the exposure of the steel plate surface increases, rust resistance will fall.

Then, the present inventors further examined the annealing separator mainly based on MgO. As a result, the present inventors contained Ca, Sr, and Ba compounds together with Y, La, Ce compounds, Ti, Zr, and Hf compounds in the annealing separator, and in terms of oxides of Y, La, Ce compounds in the annealing separator. It has been found that the depth and dispersion state of the roots of the primary coating can be adjusted by adjusting the content in the content of Ti, Zr, and Hf in terms of oxide, and the content in terms of sulfate of Ca, Sr, and Ba compounds. . Hereinafter, this point is demonstrated in detail.

The main component of the root of the primary coating is Al oxide represented by _{spinel (MgAl 2} O _{4 ).} The depth position from the surface of the Al emission intensity obtained by performing elemental analysis based on the glow discharge emission spectrometry (GDS method) from the surface of the grain-oriented electrical steel sheet in the sheet thickness direction (hereinafter referred to as the Al peak position D _Al ) is , which is considered to indicate the position of the spinel, that is, the position of the root of the primary coating. In addition, the number density of Al oxides (hereinafter referred to as Al oxide number density ND) represented by spinel having a size of 0.2 μm or more with an area-based equivalent circle diameter at the Al peak position D _{Al is the dispersion of the root of the primary film.} It is thought to indicate the state.

When the following conditions (1) to (3) are satisfied, since the root of the primary film has an appropriate length and is in an appropriate dispersed state, excellent magnetic properties and adhesion of the primary film are obtained. Moreover, since the primary film becomes dense, it is excellent in rust resistance.

(1) Al peak position D _Al is 2.4 to 12.0 µm.

(2) Al oxide number density ND is 0.03 - 0.18/micrometer<^2> .

^{(3) the ratio of the total cross-sectional area of a specific Al oxide having a cross-sectional area of 0.4 to 10.0 µm 2} among a plurality of Al oxides in the observation region at the peak position of the Al emission intensity to the total cross-sectional area of all Al oxides in the observation region ( Hereinafter, the specific Al oxide area ratio RA _AREA ) is 75.0% or more.

The above-mentioned suitable ranges of Al peak position D _Al , Al oxide number density ND and specific Al oxide area ratio RA _AREA are the average particle diameters of Y, La and Ce compounds in the annealing separator, in terms of oxides of Y, La and Ce compounds. The content of Ca, Sr, and Ba compounds in terms of sulfate, the average particle diameter of Ca, Sr, and Ba compounds, and the oxide content of Ti, Zr, and Hf compounds, and raw materials before the annealing separator is adjusted to an aqueous slurry The number density of particles of a metal compound selected from the group consisting of Y, La, and Ce in the powder, the number density of particles of a metal compound selected from the group consisting of Ti, Zr, and Hf, and Ca, Sr, Ba It can be obtained by adjusting the number density of particles of a metal compound selected from the group consisting of

The inventors found that, in the MgO-based annealing separator, the ratio of the oxide equivalent content C _RE (described later) of the Y, La, Ce compound and the oxide equivalent content C _G4 (described later) of the Ti, Zr, Hf compound and the Al peak The image showing the distribution of Al obtained by EDS analysis in the glow discharge trace region of the position D _Al ^{, and the Al oxide number density ND (piece/µm 2} ) in each image were investigated. As a result, it was found that the Al oxide number density ND was changed by adjusting the contents of the Y, La, and Ce compounds and the contents of the Ti, Zr, and Hf compounds in the annealing separator.

In addition, by adjusting the oxide content of the Y, La, Ce compound and the Ti, Zr, and Hf compound content in terms of oxide in the annealing separator, the size of the Al oxide dispersed in the observation region is also changed.

In the Al peak position D _Al , Al oxide having a cross-sectional area of ^{less than 0.4 µm 2} (hereinafter referred to as micro Al oxide) is the root of a very thin film or the root of the film that cannot fully reach the peak depth. The fine Al oxide hardly contributes to the improvement of the adhesion of the primary coating. Even with such a fine Al oxide, when the number density is increased, the film adhesion is improved. However, when the number density of the fine Al oxides increases, the primary coating does not become dense. In this case, not only the rust resistance of the grain-oriented electrical steel sheet is deteriorated, but also magnetic domain wall movement is inhibited, thereby reducing iron loss. On the other hand, Al oxides having a cross-sectional area of more than 10.0 µm ² (hereinafter, referred to as coarse Al oxides) are aggregated and adhesiveness is not effectively increased. Even in the case of coarse Al oxide, when the number density is increased, the film adhesion is improved. However, as the number density of the coarse Al oxides increases, the magnetic flux density decreases.

In the observation area, when Al oxides are ^{dispersed at 0.03 to 0.18 pieces/μm 2 , Al oxide having an area of 0.4 to 10.0 μm 2} (hereinafter referred to as specific Al oxide), which is a size capable of contributing to adhesion improvement, When the total area occupies 75% or more with respect to the total area of all Al oxides, it means that the depth position in which the specific Al oxide exists is consistent. This means that, in the primary film, the size of the Al oxide is uniform (that is, there are many specific Al oxides), and the primary film is dense. Therefore, the rust resistance of the grain-oriented electrical steel sheet is improved, and good magnetic properties and good film adhesion are also obtained.

The above-mentioned primary film can be produced by using the following annealing separator. The annealing separator suitable for the grain-oriented electrical steel sheet of the present invention contains MgO, Y, La, Ce compounds, Ti, Zr, Hf compounds, and Ca, Sr, Ba compounds, and contains MgO content in the annealing separator by mass When 100% in %, the total content in terms of oxides of Y, La, and Ce compounds is 0.8 to 8.0%, the total content in terms of oxides of Ti, Zr, and Hf compounds is 0.5 to 9.0%, Ca, Sr, The total content of the Ba compound in terms of sulfate is 0.5 to 8.0%. In the annealing separator, the average particle diameter of Ca, Sr, and Ba compounds is 12 μm or less, the ratio of the average particle diameter of Ca, Sr, and Ba compounds to the average particle diameter of Y, La, and Ce compounds is 0.1 to 3.0, Y , La and Ce compounds in terms of oxide content and the total content in terms of oxides of Ti, Zr, and Hf compounds are 2.0 to 12.5%, and the total number of Ti, Zr and Hf atoms contained in the annealing separator is The ratio of the total number of Y, La, and Ce atoms is 0.18 to 4.0, and in the raw material powder before the annealing separator is adjusted to an aqueous slurry, the metal compound selected from the group consisting of Y, La, Ce The number density of particles having a particle diameter of 0.1 μm or more, the number density of the metal compound selected from the group consisting of Ti, Zr, and Hf of 0.1 μm or more, and the particle diameter of the metal compound selected from the group consisting of Ca, Sr, and Ba 0.1 The number density of particles of ㎛ or larger is 2 billion/g or more. When this annealing separator is used, even in a grain-oriented electrical steel sheet manufactured from a hot-rolled steel sheet containing magnetic flux density improving elements (Sn, Sb, Bi, Te, Pb, etc.), in the primary film, Al peak position D _Al is 2.4 to 12.0 µm, and the number density ND of Al oxides having a size of 0.2 µm or more in terms of area-based equivalent circle diameter is 0.03 to 0.18 pieces/µm ² , and 30 µm×50 at the peak position of the Al emission intensity In the observation region of μm, the specific Al oxide area ratio RA _AREA is 75.0% or more. As a result, excellent magnetic properties and adhesion of the primary film, and excellent rust resistance are obtained.

A grain-oriented electrical steel sheet according to the present invention completed based on the above findings, in mass%, C: 0.005% or less, Si: 2.5 to 4.5%, Mn: 0.02 to 0.2%, and one selected from the group consisting of S and Se or more elements: 0.005% or less in total, sol. Al: 0.01% or less, and N: 0.01% or less, the balance being formed on the surface of a base steel sheet having a chemical composition containing Fe and impurities, and containing Mg ₂ SiO ₄ as a main component A primary coating is provided. The peak position of the Al emission intensity obtained when elemental analysis by glow discharge emission spectrometry is performed from the surface of the primary film in the thickness direction of the grain-oriented electrical steel sheet is 2.4 to 12.0 µm from the surface of the primary film to the thickness direction a plurality of Al oxides arranged within the range, the number density of Al oxides at the peak position of Al emission intensity is 0.03 to 0.18 pieces/µm ² Among them, the total cross-sectional area of the specific Al oxide having a cross-sectional area of 0.4 to 10.0 µm ² is 75.0% or more of the total cross-sectional area of all Al oxides in the observation region.

The method for manufacturing a grain-oriented electrical steel sheet according to the present invention comprises, in mass%, C: 0.1% or less, Si: 2.5 to 4.5%, Mn: 0.02 to 0.2%, and at least one element selected from the group consisting of S and Se: 0.005 to 0.07% in total, sol. Al: 0.005 to 0.05%, and N: 0.001 to 0.030%, the balance is subjected to cold rolling at a cold rolling rate of 80% or more with respect to a hot-rolled steel sheet containing Fe and impurities to produce a cold-rolled steel sheet serving as a base steel sheet The step of performing decarburization annealing on the cold rolled steel sheet, and applying an aqueous slurry containing an annealing separator to the surface of the cold rolled steel sheet after decarburization annealing, and an aqueous slurry on the surface of the cold rolled steel sheet in a furnace at 400 to 1000°C It is provided with the process of drying and the process of performing finish annealing with respect to the cold-rolled steel sheet after the aqueous slurry has dried. The annealing separator includes MgO and at least one compound of a metal selected from the group consisting of Y, La, and Ce, and at least one compound of a metal selected from the group consisting of Ti, Zr, and Hf. , Ca, Sr, containing at least one compound of a metal selected from the group consisting of Ba, and when the MgO content in the annealing separator is 100% by mass%, selected from the group consisting of Y, La, Ce The total oxide content of the compound to be used is 0.8 to 8.0%, the total oxide content of the metal compound selected from the group consisting of Ti, Zr, and Hf is 0.5 to 9.0%, the group consisting of Ca, Sr, and Ba The total content in terms of sulfate of the metal compound selected from is 0.5 to 8.0%, the average particle diameter of the metal compound selected from the group consisting of Ca, Sr, and Ba is 12 µm or less, and the group consisting of Ca, Sr, and Ba The ratio of the average particle diameter of the compound of the metal selected from the group consisting of Y, La, and Ce to the average particle diameter of the compound of the metal selected from the group is 0.1 to 3.0, and the compound of the metal selected from the group consisting of Y, La, and Ce The sum of the total content in terms of oxide and the total content in terms of oxide of a metal compound selected from the group consisting of Ti, Zr, and Hf is 2.0 to 12.5%, and the number of Ti, Zr, and Hf atoms contained in the annealing separator is The ratio of the sum of the number of Y, La, and Ce atoms to the total is 0.18 to 4.0, and the particle size of the metal compound selected from the group consisting of Y, La and Ce in the raw material powder before the annealing separator is adjusted to the aqueous slurry. The number density of particles of 0.1 μm or more, the number density of particles having a particle diameter of 0.1 μm or more of a metal compound selected from the group consisting of Ti, Zr, and Hf, and a particle diameter of 0.1 μm or more of a metal compound selected from the group consisting of Ca, Sr, and Ba The number density of the particle|grains is 2 billion pieces/g or more, respectively. However, the particle diameter is a sphere equivalent diameter on a volume basis.

In the method for manufacturing a grain-oriented electrical steel sheet, the chemical composition of the hot-rolled steel sheet may contain 0.6% or less in total of at least one element selected from the group consisting of Cu, Sb, and Sn instead of a part of Fe.

In the method for manufacturing a grain-oriented electrical steel sheet, the chemical composition of the hot-rolled steel sheet may contain, in total, 0.03% or less of at least one element selected from the group consisting of Bi, Te, and Pb instead of a part of Fe.

The annealing separator according to the present invention is used for the production of grain-oriented electrical steel sheet. The annealing separator includes MgO and at least one compound of a metal selected from the group consisting of Y, La, and Ce, and at least one compound of a metal selected from the group consisting of Ti, Zr, and Hf; It contains at least one compound of a metal selected from the group consisting of Ca, Sr, and Ba, and when the MgO content in the annealing separator is 100% by mass%, selected from the group consisting of Y, La, and Ce The total oxide content of the compound is 0.8 to 8.0%, the total oxide content of the metal compound selected from the group consisting of Ti, Zr, and Hf is 0.5 to 9.0%, in the group consisting of Ca, Sr, and Ba The total content of the selected metal compound in terms of sulfate is 0.5 to 8.0%, the average particle diameter of the metal compound selected from the group consisting of Ca, Sr, and Ba is 12 µm or less, and in the group consisting of Ca, Sr, and Ba The ratio of the average particle diameter of the compound of the selected metal to the average particle diameter of the compound of the metal selected from the group consisting of Y, La, and Ce is 0.1 to 3.0, and the compound of the metal selected from the group consisting of Y, La, and Ce The sum of the total content in terms of oxide and the total content in terms of oxide of a metal compound selected from the group consisting of Ti, Zr, and Hf is 2.0 to 12.5%, and the number of Ti, Zr, and Hf atoms contained in the annealing separator is The ratio of the sum of the number of Y, La, and Ce atoms to the total is 0.18 to 4.0, and the particle size of the metal compound selected from the group consisting of Y, La and Ce in the raw material powder before the annealing separator is adjusted to the aqueous slurry. The number density of particles of 0.1 μm or more, the number density of particles having a particle diameter of 0.1 μm or more of a metal compound selected from the group consisting of Ti, Zr, and Hf, and a particle diameter of 0.1 μm or more of a metal compound selected from the group consisting of Ca, Sr, and Ba The number density of each particle is 2 billion/g or more.

Hereinafter, a grain-oriented electrical steel sheet according to the present invention, a method for manufacturing a grain-oriented electrical steel sheet, and an annealing separator used for manufacturing a grain-oriented electrical steel sheet will be described in detail. In this specification, % regarding content of an element means mass % unless otherwise indicated. In addition, the notation "A to B" with respect to numerical value A and B shall mean "A or more and B or less". In this notation, when a unit is attached only to the numerical value B, the unit shall also be applied to the numerical value A.

[Composition of grain-oriented electrical steel sheet]

A grain-oriented electrical steel sheet according to the present invention includes a base steel sheet and a primary film formed on the surface of the base steel sheet.

[Chemical composition of base steel sheet]

The chemical composition of the base steel sheet constituting the grain-oriented electrical steel sheet described above contains the following elements. In addition, as demonstrated in the manufacturing method mentioned later, a base steel plate is manufactured by cold rolling using the hot-rolled steel plate which has the chemical composition mentioned later.

C: 0.005% or less

Carbon (C) is an element effective for controlling the structure up to the completion of the decarburization annealing process during the manufacturing process. However, when the C content exceeds 0.005%, the magnetic properties of the grain-oriented electrical steel sheet as a product sheet deteriorate. Therefore, the C content is 0.005% or less. The C content is preferably as low as possible. However, even if the C content is reduced to less than 0.0001%, manufacturing cost is only required, and the above effect does not change much. Therefore, the preferable lower limit of the C content is 0.0001%.

Si: 2.5 to 4.5%

Silicon (Si) increases the electrical resistance of the steel and reduces eddy current losses. When Si content is less than 2.5 %, the said effect is not fully acquired. On the other hand, when Si content exceeds 4.5 %, cold workability of steel will fall. Therefore, the Si content is 2.5 to 4.5%. The preferable lower limit of Si content is 2.6 %, More preferably, it is 2.8 %. The preferable upper limit of Si content is 4.0 %, More preferably, it is 3.8 %.

Mn: 0.02 to 0.2%

Manganese (Mn) forms MnS and MnSe by combining with S and Se, which will be described later, during the manufacturing process. These precipitates function as inhibitors (inhibitors of normal grain growth) and cause secondary recrystallization in steel. Mn also increases the hot workability of the steel. When Mn content is less than 0.02 %, the said effect is not fully acquired. On the other hand, when the Mn content exceeds 0.2%, secondary recrystallization does not occur and the magnetic properties of the steel deteriorate. Therefore, the Mn content is 0.02 to 0.2%. A preferable lower limit of the Mn content is 0.03%, more preferably 0.04%. A preferable upper limit of the Mn content is 0.13%, more preferably 0.10%.

At least one element selected from the group consisting of S and Se: 0.005% or less in total

Sulfur (S) and selenium (Se) combine with Mn during the manufacturing process to form MnS and MnSe functioning as inhibitors. However, when the content of these elements in total exceeds 0.005%, the magnetic properties deteriorate due to the remaining inhibitor. In addition, surface defects may occur in the grain-oriented electrical steel sheet due to segregation of S and Se. Therefore, in the grain-oriented electrical steel sheet, the total content of at least one selected from the group consisting of S and Se is 0.005% or less. It is preferable that the sum total of S and Se content in a grain-oriented electrical steel sheet is as low as possible. However, even if the total of the S content and the Se content in the grain-oriented electrical steel sheet is reduced to 0.0005%, the manufacturing cost is only required, and the effect does not change much. Therefore, the preferable lower limit of the total content of at least one selected from the group consisting of S and Se in the grain-oriented electrical steel sheet is 0.0005%.

sol. Al: 0.01% or less

Aluminum (Al) combines with N during the manufacturing process of a grain-oriented electrical steel sheet to form AlN, and functions as an inhibitor. However, in the grain-oriented electrical steel sheet, sol. When the Al content exceeds 0.01%, the above-mentioned inhibitor excessively remains in the steel sheet, so that the magnetic properties are deteriorated. Therefore, sol. The Al content is 0.01% or less. sol. The preferable upper limit of Al content is 0.004 %, More preferably, it is 0.003 %. sol. The Al content is preferably as low as possible. However, in the grain-oriented electrical steel sheet, sol. Even if the Al content is reduced to 0.0001%, manufacturing cost is only required, and the above effect does not change much. Therefore, in the grain-oriented electrical steel sheet, sol. A preferable lower limit of the Al content is 0.0001%. In addition, in the present specification, sol. Al means Al for acid value. Therefore, sol. Al content is content of Al for acid value.

N: 0.01% or less

Nitrogen (N) combines with Al to form AlN during the manufacturing process of the grain-oriented electrical steel sheet, and functions as an inhibitor. However, when the N content in the grain-oriented electrical steel sheet exceeds 0.01%, the above-mentioned inhibitors remain excessively in the grain-oriented electrical steel sheet, and thus the magnetic properties are deteriorated. Therefore, the N content is 0.01% or less. A preferable upper limit of the N content is 0.004%, more preferably 0.003%. The N content is preferably as low as possible. However, even if the total N content in the grain-oriented electrical steel sheet is reduced to 0.0001%, manufacturing cost is only required, and the above effect does not change much. Therefore, the preferable lower limit of the N content in the grain-oriented electrical steel sheet is 0.0001%.

The balance of the chemical composition of the base steel sheet of the grain-oriented electrical steel sheet according to the present invention contains Fe and impurities. Here, the impurity refers to the following elements that remain in the steel without being completely purified in purifying annealing or the like mixed with ore, scrap, or manufacturing environment as raw materials when industrially manufacturing the base steel sheet, and the like, of the present invention. It means that it is allowed in a range that does not adversely affect the grain-oriented electrical steel sheet.

[About impurities]

The total content of at least one selected from the group consisting of Cu, Sn, Sb, Bi, Te and Pb in the impurities in the base steel sheet of the grain-oriented electrical steel sheet according to the present invention is 0.30% or less.

Copper (Cu), tin (Sn), antimony (Sb), bismuth (Bi), tellurium (Te) and lead (Pb) are subjected to high-temperature heat treatment, also called “purification annealing,” in one step of finish annealing, Some of Cu, Sn, Sb, Bi, Te, and Pb in the steel sheet are discharged to the outside of the system. These elements exert an effect of improving the magnetic flux density by increasing the orientation selectivity of secondary recrystallization in the finish annealing, but if they remain in the grain-oriented electrical steel sheet after the finish annealing is completed, they are simple impurities and deteriorate the iron loss. Therefore, the total content of at least one element selected from the group consisting of Cu, Sn, Sb, Bi, Te and Pb is 0.30% or less. Since these elements are impurities as described above, the total content of these elements is preferably as low as possible.

[primary film]

The grain-oriented electrical steel sheet according to the present invention also includes the primary coating as described above. The primary film is formed on the surface of the base steel sheet. The main component of the primary film is forsterite (Mg ₂ SiO ₄ ). More specifically, the primary film contains 50 to 90 mass % of Mg ₂ SiO ₄ .

In addition, although the main component of the primary film is Mg ₂ SiO ₄ as described above, the primary film also contains Ce, Zr and Ca. The Ce content in the primary coating is 0.001 to 8.0%. The Zr content in the primary coating is 0.0005 to 4.0%. The Ca content in the primary coating is 0.0005 to 4.0%.

As described above, in the present invention, in the method for manufacturing a grain-oriented electrical steel sheet, an annealing separator containing Ti, Zr, Hf compounds and Ca, Sr, Ba compounds is used together with the Y, La, and Ce compounds described above. . Thereby, the magnetic properties of the grain-oriented electrical steel sheet can be improved, and the coating adhesion and rust resistance of the primary coating can also be improved. Since Y, La, Ce compounds, Ti, Zr, Hf compounds and Ca, Sr, Ba compounds are contained in the annealing separator, the primary film also contains Y, La, Ce, Ti, Zr, Hf, It contains Ca, Sr and Ba.

_{The Mg 2} SiO ₄ content in the primary coating can be measured by the following method. The grain-oriented electrical steel sheet is electrolyzed to separate the primary coating layer from the surface of the base steel sheet. Mg in the separated primary film is quantitatively analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The obtained quantitative value (mass%) of the product of the Mg ₂ SiO ₄ molecular weight, divided by the atomic weight of Mg is determined by the content of Mg ₂ SiO ₄ eq.

The Y, La, Ce, Ti, Zr, Hf, Ca, Sr and Ba contents in the primary coating can be measured by the following method. The grain-oriented electrical steel sheet is electrolyzed to separate the primary coating layer from the surface of the base steel sheet. Y, La, Ce content (mass %), Ti, Zr, Hf content (mass %), and Ca, Sr, Ba content (mass %) in the separated primary film were quantitatively analyzed by ICP-MS.

[Peak position of Al emission intensity by GDS method]

In the grain-oriented electrical steel sheet according to the present invention, the peak position of the Al emission intensity obtained when elemental analysis by the glow discharge emission spectrometry method is performed from the surface of the primary film to the thickness direction of the grain-oriented electrical steel sheet is the surface of the primary film It is arranged in the range of 2.4 to 12.0 µm in the plate thickness direction.

In the grain-oriented electrical steel sheet, the interface between the primary film and the steel sheet (now) has a fitting structure. Specifically, a part of the primary coating enters the inside of the steel sheet from the surface of the steel sheet. A part of the primary coating that has entered the inside of the steel plate from the surface of the steel plate exhibits a so-called anchor effect, thereby enhancing the adhesion of the primary coating to the steel plate. Hereinafter, in this specification, a part of the primary film entering the inside of the steel sheet from the surface of the steel sheet is defined as "the root of the primary film."

In the region where the root of the primary coating is deeply embedded in the steel sheet, the main component of the root of the primary coating is spinel (MgAl ₂ O ₄ ), which is a type of Al oxide. The peak of Al emission intensity obtained when elemental analysis by the glow discharge emission spectrometry is performed has shown the presence position of the said spinel.

The depth position of the Al emission intensity peak from the primary film surface _{is defined as Al peak position D Al} (μm). When the Al peak position D _Al is less than 2.4 μm, it means that the spinel is formed at a shallow (lower) position from the surface of the steel sheet. That is, it means that the root of the primary film is shallow. In this case, the adhesiveness of the primary film is low. On the other hand, when the Al peak position D _Al exceeds 12.0 μm, the root of the primary film is excessively developed, and the root of the primary film enters the deep part of the steel sheet. In this case, the root of the primary coating inhibits the movement of the magnetic domain wall. As a result, the magnetic properties are lowered.

When Al peak position D _Al is 2.4 to 12.0 µm, the adhesion of the film can be improved while maintaining excellent magnetic properties. The preferable lower limit of Al peak position D _Al is 3.0 micrometers, More preferably, it is 4.0 micrometers. The preferable upper limit of Al peak position D _Al is 11.0 micrometer, More preferably, it is 10.0 micrometer.

Al peak position D _Al can be measured by the following method. Elemental analysis is performed using a well-known glow discharge emission spectrometry (GDS method). Specifically, the Ar atmosphere is used on the surface of the grain-oriented electrical steel sheet. A voltage is applied to the grain-oriented electrical steel sheet to generate glow plasma, and the surface layer of the steel sheet is analyzed in the thickness direction while sputtering.

Al contained in the surface layer of the steel sheet is identified based on the emission spectrum wavelength peculiar to the element generated by the excited atoms in the glow plasma. In addition, the emission intensity of the identified Al is plotted in the depth direction. Based on the plotted Al emission intensity, the Al peak position D _Al is found.

The depth position from the surface of the primary film in elemental analysis can be calculated based on sputtering time. Specifically, in a standard sample, the relationship between sputtering time and sputtering depth (henceforth a sample result) is calculated|required beforehand. Using the sample results, convert sputter time to sputter depth. The converted sputtering depth is defined as a depth position (a depth position from the surface of the primary film) subjected to elemental analysis (Al analysis). In the GDS method in the present invention, a commercially available high-frequency glow discharge emission spectrometer can be used.

[Number density ND of Al oxides having a size of 0.2 µm or more in discharge traces]

In the grain-oriented electrical steel sheet according to the present invention, the number density ND of Al oxides having a size of 0.2 µm or more in terms of the area-based equivalent circle diameter at the _{Al peak position D Al} ^{is 0.03 to 0.18 pieces/µm 2} .

As described above, the Al peak position D _Al corresponds to the root portion of the primary coating. _{Spinel (MgAl 2} O ₄ ), which is an Al oxide, is abundant at the root of the primary film. Therefore, when the Al oxide number density ND is defined as the number density of Al oxides in an arbitrary region (for example, the bottom of the discharge trace of the glow discharge) at the Al peak position D _{Al, the Al oxide number density ND is} It is an index indicating the dispersion state of the root (spinel) of the primary coating in the surface layer of the steel sheet.

When the Al oxide number density ND is ^{less than 0.03/μm 2} , the roots of the primary coating are not sufficiently formed. Therefore, the adhesiveness with respect to the steel plate of a primary film is low. On the other hand, when the Al oxide number density ND exceeds 0.18/μm ² , the roots of the primary film are excessively developed, and the roots of the primary film enter deep inside the steel sheet. In this case, the root of the primary film inhibits secondary recrystallization and magnetic domain wall movement, and the magnetic properties are deteriorated. Accordingly, the Al oxide number density ND is 0.03 to 0.18/μm ² . The preferable lower limit of the Al oxide number density ND is 0.035/μm ² , and more preferably 0.04/μm ² . A preferable upper limit of the number density ND is 0.15 pieces/μm ² , and more preferably 0.1 pieces/μm ² .

Al oxide number density ND can be calculated|required by the following method. A glow discharge is performed to Al peak position D _{Al with a glow discharge emission spectrometer.} Elemental analysis by an energy dispersive X-ray spectroscopy (EDS) is performed on an arbitrary 30 µm x 50 µm region (observation region) among the discharge traces at the Al peak position D _{Al, and X-rays characteristic of the observation region} A map showing intensity distribution is created, and Al oxide is specified. Specifically, a region in which the intensity of the characteristic X-ray of O of 50% or more is analyzed with respect to the maximum intensity of the characteristic X-ray of oxygen (O) in the observation region is specified as an oxide. In the specified oxide region, with respect to the maximum intensity of the specific X-ray of Al, a region in which 30% or more of the specific X-ray intensity of Al is analyzed is specified as Al oxide. The specified Al oxide is mainly spinel, and other than that, there is a possibility that it is a silicate containing various alkaline earth metals and Al in a high concentration. Among the specified Al oxides, the number of Al oxides having a size of 0.2 µm or more is counted with an area-based equivalent circle diameter, and the Al oxide number density ND (pieces/µm ² ) is calculated by the following formula.

Equivalent circle diameter = √(4/π·(Area of the region specified by Al oxide (Area per analysis point in the map showing distribution of characteristic X-ray intensity x analysis score corresponding to the region specified by Al oxide))

Area per analysis point = area of observation area ÷ analysis score in a map showing distribution of characteristic X-ray intensities

ND = number of specified Al oxides with a circle equivalent diameter of 0.2 µm or more/area of observation area

If the Ce content in the primary film is 0.001 to 8.0%, the Zr content in the primary film is 0.0005 to 4.0%, and the Ca content in the primary film is 0.0005 to 4.0%, the Al peak position D _Al is 2.4 to 12.0 µm and the number density ND of Al oxides at the Al peak position D _Al ^{is 0.03 to 0.18 pieces/µm 2} .

[Specific Al oxide area ratio RA _AREA ]

In the grain-oriented electrical steel sheet according to the present invention, in the observation area of 30 µm × 50 µm at the _{Al peak position D Al} , among the plurality of Al oxides, the total area of specific Al oxides ^{having an area of 0.4 to 10.0 µm 2} _{, the ratio (specific Al oxide area ratio RA AREA} ) to the total area of all Al oxides in the observation region is 75.0% or more. The area of the observation region may be, for example, an arbitrary 30 µm×50 µm region, and may be arbitrarily selected at the _{Al peak position D Al.}

As described above, the Al peak position D _Al corresponds to the root portion of the primary coating. _{Spinel (MgAl 2} O ₄ ), which is an Al oxide, is abundant at the root of the primary film. Therefore, the specific Al oxide area ratio RA _AREA represents the dispersion state of the root (Al oxide) of the primary coating, similarly to the Al oxide number density ND.

In the observation area of 30 µm x 50 µm ^{, when the total area of Al oxides having an area of 0.4 to 10.0 µm 2} among the plurality of Al oxides is 75.0% or more of the total area of all Al oxides in the observation area, for improving the adhesion It means that the depth position of the specific Al oxide that can contribute is matched. This means that the size of the Al oxide particles in the obtained primary film is almost uniform, and the primary film is dense.

When the specific Al oxide area ratio RA _AREA is too low, the primary film is not dense and the rust resistance is lowered. Therefore, the specific Al oxide area ratio RA _AREA is 75.0% or more. A preferred specific Al oxide area ratio RA _AREA is 84.0% or more, more preferably 90.0% or more.

In addition, in the observation region, if the area of the Al oxide is ^{less than 0.4 µm 2} , it does not sufficiently grow as a root of the primary coating. On the other hand, when the area of the Al oxide ^{exceeds 10.0 μm 2} , the root of the primary film is excessively developed. As a result, the primary coating film is not dense, and rust resistance is lowered.

The specific Al oxide area ratio RA _AREA can be obtained by the following method. A glow discharge is performed to Al peak position D _{Al with a glow discharge emission spectrometer.} Among the discharge traces at the Al peak position D _Al , an elemental analysis using an energy dispersive X-ray spectroscopy (EDS) was performed on an arbitrary region (observation region) of 30 μm × 50 μm to determine Al oxide in the observation region. specify Specifically, a region in which the intensity of the characteristic X-ray of O of 50% or more is analyzed with respect to the maximum intensity of the characteristic X-ray of oxygen (O) in the observation region is specified as an oxide. In the specified oxide region, with respect to the maximum intensity of the specific X-ray of Al, a region in which 30% or more of the specific X-ray intensity of Al is analyzed is specified as Al oxide. The specified Al oxide is mainly spinel, and other than that, there is a possibility that it is a silicate containing various alkaline earth metals and Al in a high concentration. Based on the measurement result, a distribution diagram of Al oxide in the observation region is created. The area of the observation region may be, for example, 30 µm x 50 µm, and may be selected from _{any Al peak position D Al.}

In the prepared distribution map (observation region), the area of each Al oxide is calculated. Based on the calculation result, Al oxide having an area of 0.4 to 10.0 µm ² in the distribution diagram is recognized as a specific Al oxide. Find the total area of a specific recognized Al oxide. Further, the total area of all Al oxides in the distribution diagram is obtained, and the specific Al oxide area ratio RA _AREA is obtained based on the following equation.

Specific Al oxide area ratio RA _AREA = Total area of specific Al oxides in observation area/Total area of all Al oxides in observation area×100

[Manufacturing method]

An example of the manufacturing method of the grain-oriented electrical steel sheet by this invention is demonstrated.

An example of the method for manufacturing a grain-oriented electrical steel sheet includes a cold rolling process, a decarburization annealing process, and a finish annealing process. Hereinafter, each process is demonstrated.

[Cold rolling process]

At a cold rolling process, it cold-rolls with respect to a hot-rolled steel plate, and manufactures a cold-rolled steel plate. The hot rolled steel sheet contains the following chemical composition.

C: 0.1% or less;

When the C content in the hot-rolled steel sheet exceeds 0.1%, the time required for decarburization annealing becomes long. In this case, manufacturing cost becomes high, and productivity also falls. Therefore, the C content of the hot-rolled steel sheet is 0.1% or less. A preferable upper limit of the C content of the hot-rolled steel sheet is 0.092%, more preferably 0.085%. The lower limit of the C content of the hot-rolled steel sheet is 0.005%, preferably 0.02%, and more preferably 0.04%.

Si: 2.5 to 4.5%,

As explained in the item of the chemical composition of the grain-oriented electrical steel sheet, which is a product, Si increases the electrical resistance of the steel, but when it is contained in excess, the cold workability deteriorates. When the Si content of the hot-rolled steel sheet is 2.5 to 4.0%, the Si content of the grain-oriented electrical steel sheet after the final annealing step is 2.5 to 4.5%. A preferable upper limit of the Si content of the hot-rolled steel sheet is 4.0%, more preferably 3.8%. A preferable lower limit of the Si content of the hot-rolled steel sheet is 2.6%, more preferably 2.8%.

Mn: 0.02 to 0.2%

As described in the item of the chemical composition of the grain-oriented electrical steel sheet as a product, during the manufacturing process, Mn combines with S and Se to form a precipitate, and functions as an inhibitor. Mn also increases the hot workability of the steel. When the Mn content of the hot-rolled steel sheet is 0.02 to 0.2%, the Mn content of the grain-oriented electrical steel sheet after the final annealing step is 0.02 to 0.2%. A preferable upper limit of the Mn content of the hot-rolled steel sheet is 0.13%, more preferably 0.1%. A preferable lower limit of the Mn content of the hot-rolled steel sheet is 0.03%, more preferably 0.04%.

At least one element selected from the group consisting of S and Se: 0.005 to 0.07% in total

During the manufacturing process, sulfur (S) and selenium (Se) combine with Mn to form MnS and MnSe. Both MnS and MnSe function as inhibitors necessary to suppress grain growth during secondary recrystallization. When the total content of at least one element selected from the group consisting of S and Se is less than 0.005%, the above effect is difficult to be obtained. On the other hand, when the total content of at least one element selected from the group consisting of S and Se exceeds 0.07%, secondary recrystallization does not occur during the manufacturing process, and the magnetic properties of the steel decrease. Therefore, in the hot-rolled steel sheet, the total content of at least one element selected from the group consisting of S and Se is 0.005 to 0.07%. A preferable lower limit of the total content of at least one element selected from the group consisting of S and Se is 0.008%, more preferably 0.016%. A preferable upper limit of the total content of at least one element selected from the group consisting of S and Se is 0.06%, more preferably 0.05%.

sol. Al: 0.005 to 0.05%

During the manufacturing process, aluminum (Al) combines with N to form AlN. AlN functions as an inhibitor. sol in hot rolled steel sheet. When the Al content is less than 0.01%, the above effect cannot be obtained. On the other hand, sol. When the Al content exceeds 0.05%, AlN coarsens. In this case, it becomes difficult for AlN to function as an inhibitor, and secondary recrystallization does not occur in some cases. Therefore, sol in the hot-rolled steel sheet. The Al content is 0.005 to 0.05%. sol in hot rolled steel sheet. The preferable upper limit of Al content is 0.04 %, More preferably, it is 0.035 %. sol in hot rolled steel sheet. The preferable lower limit of Al content is 0.01 %, More preferably, it is 0.015 %.

N: 0.001 to 0.030%

During the manufacturing process, nitrogen (N) combines with Al to form AlN functioning as an inhibitor. When the N content in the hot-rolled steel sheet is less than 0.001%, the above effect cannot be obtained. On the other hand, when the N content in the hot-rolled steel sheet exceeds 0.030%, AlN coarsens. In this case, it becomes difficult for AlN to function as an inhibitor, and secondary recrystallization does not occur in some cases. Therefore, the N content in the hot-rolled steel sheet is 0.001 to 0.030%. A preferable upper limit of the N content in the hot-rolled steel sheet is 0.012%, more preferably 0.010%. A preferable lower limit of the N content in the hot-rolled steel sheet is 0.005%, more preferably 0.006%.

The remainder of the chemical composition of the hot-rolled steel sheet of the present invention includes Fe and impurities. Here, the impurity means that when a hot-rolled steel sheet is industrially manufactured, it is mixed from ore as a raw material, scrap, or a manufacturing environment, etc., and it means that it is permissible in the range which does not adversely affect the hot-rolled steel sheet of this embodiment.

[About arbitrary elements]

The hot-rolled steel sheet according to the present invention may further contain 0.6% or less in total of one or more elements selected from the group consisting of Cu, Sn and Sb instead of a part of Fe. All of these elements are arbitrary.

At least one element selected from the group consisting of Cu, Sn and Sb: 0 to 0.6% in total

Copper (Cu), tin (Sn), and antimony (Sb) are all optional elements and do not need to be contained. When contained, Cu, Sn and Sb all increase the magnetic flux density of the grain-oriented electrical steel sheet. When even a little of Cu, Sn and Sb are contained, the said effect is acquired to some extent. However, when Cu, Sn, and Sb content exceeds 0.6 % in total, it becomes difficult to form an internal oxide layer at the time of decarburization annealing. In this case, during the final annealing, MgO of the annealing separator and SiO ₂ of the internal oxide layer react to delay the formation of the primary film. As a result, the adhesiveness of a primary film falls. Moreover, Cu, Sn, and Sb tend to remain|survive as impurity elements after purifying annealing. As a result, the magnetic properties deteriorate. Therefore, the content of at least one element selected from the group consisting of Cu, Sn and Sb is 0 to 0.6% in total. A preferable lower limit of the total content of at least one element selected from the group consisting of Cu, Sn and Sb is 0.005%, more preferably 0.007%. A preferable upper limit of the total content of at least one element selected from the group consisting of Sn and Sb is 0.5%, more preferably 0.45%.

The hot-rolled steel sheet according to the present invention may further contain 0.03% or less in total of at least one element selected from the group consisting of Bi, Te and Pb instead of a part of Fe. All of these elements are arbitrary.

At least one element selected from the group consisting of Bi, Te and Pb: 0 to 0.03% in total

Bismuth (Bi), tellurium (Te), and lead (Pb) are all optional elements and do not need to be contained. When contained, Bi, Te and Pb all increase the magnetic flux density of the grain-oriented electrical steel sheet. When any of these elements is contained, this effect is obtained to some extent. However, when the total content of these elements exceeds 0.03%, these elements are segregated on the surface during finish annealing, and the interface between the primary coating film and the steel sheet is flattened. In this case, the film adhesiveness of a primary film falls. Therefore, the total content of at least one element selected from the group consisting of Bi, Te and Pb is 0 to 0.03%. A preferable lower limit of the total content of at least one element selected from the group consisting of Bi, Te and Pb is 0.0005%, more preferably 0.001%. A preferable upper limit of the total content of at least one element selected from the group consisting of Bi, Te and Pb is 0.02%, more preferably 0.015%.

A hot-rolled steel sheet having the above-described chemical composition is manufactured by a known method. An example of the manufacturing method of a hot-rolled steel sheet is as follows. A slab having the same chemical composition as the above-described hot-rolled steel sheet is prepared. A slab is manufactured by implementing a well-known refining process and a casting process. Heat the slab. The heating temperature of the slab is, for example, greater than 1280°C to 1350°C. Hot rolling is performed on the heated slab to manufacture a hot rolled steel sheet.

Cold rolling is performed on the prepared hot-rolled steel sheet to manufacture a cold-rolled steel sheet, which is a base steel sheet. Cold rolling may be performed only once, and may be performed in multiple times. When performing cold rolling in multiple times, after performing cold rolling, intermediate annealing for the purpose of softening is performed, and cold rolling is performed after that. Cold rolling is performed once or several times, and the cold-rolled steel plate which has a product plate|board thickness (plate|board thickness as a product) is manufactured.

The cold rolling rate in one time or multiple times of cold rolling is 80 % or more. Here, the cold rolling rate (%) is defined as follows.

Cold rolling rate (%) = (1-thickness of cold-rolled steel sheet after the last cold rolling/thickness of hot-rolled steel sheet before the start of first cold rolling) x 100

In addition, the preferable upper limit of a cold rolling rate is 95 %. In addition, before performing cold rolling with respect to a hot-rolled steel plate, you may heat-process with respect to a hot-rolled steel plate, and you may perform pickling.

[Decarburization Annealing Process]

Decarburization annealing is performed with respect to the steel plate manufactured by the cold rolling process, and nitridation annealing is performed as needed. The decarburization annealing is performed in a well-known hydrogen-nitrogen containing wet atmosphere. By decarburization annealing, the C concentration of the grain-oriented electrical steel sheet is reduced to 50 ppm or less capable of suppressing deterioration of self-aging. In decarburization annealing, primary recrystallization is also expressed in the steel sheet, and the working strain introduced by the cold rolling process is released. In the decarburization annealing process, the internal oxide layer mainly composed of SiO ₂ is formed on the surface layer of the steel sheet. The annealing temperature in decarburization annealing is well-known, for example, 750-950 degreeC. The holding time at the annealing temperature is, for example, 1 to 5 minutes.

[Finish annealing process]

A finish annealing process is performed on the steel sheet after the decarburization annealing process. In the finish annealing step, first, an aqueous slurry containing an annealing separator is applied to the surface of a steel sheet. And annealing (finish annealing) is performed with respect to the steel plate which apply|coated the aqueous slurry.

[About aqueous slurry]

The aqueous slurry is purified by adding industrial pure water to an annealing separator described later, followed by stirring. What is necessary is just to determine the ratio of annealing separator and industrial pure water so that it may become a required application amount when apply|coating with a roll coater, For example, 2 times or more and 20 times or less are preferable. When the ratio of water to the annealing separator is less than 2, the viscosity of the water slurry becomes too high, so that the annealing separator cannot be uniformly applied to the surface of the steel sheet, which is not preferable. When the ratio of water to the annealing separator is more than 20 times, drying of the water slurry in the subsequent drying process becomes insufficient, and the moisture remaining in the finish annealing further oxidizes the steel sheet, which is not preferable because the appearance of the primary film deteriorates. not.

[About annealing separator]

In the present invention, the annealing separator used in the finish annealing step contains magnesium oxide (MgO) and an additive. MgO is a main component of the annealing separator, and "main component" means a component contained in a certain substance at 50 mass % or more, preferably 70 mass % or more, more preferably 90 mass % or more. Adhesion amount of the annealing separator of the steel sheet per one surface, for example, 2g / m ² more than 10g / m ² or less. When the adhesion amount of the annealing separator to the steel sheet is ^{less than 2} g/m 2 , in the final annealing, the steel sheets are seized, which is not preferable. When the adhesion amount of the annealing separator to the steel sheet ^{exceeds 10 g/m 2} , it is not preferable because manufacturing cost increases. The application of the annealing separator may be an electrostatic application or the like instead of the application with an aqueous slurry.

The additive includes at least one compound of a metal selected from the group consisting of Y, La, and Ce, and at least one compound of a metal selected from the group consisting of Ti, Zr, and Hf, and Ca, Sr, Ba When at least one compound of a metal selected from the group consisting of The total content is 0.8 to 8.0%, the total content in terms of oxides of the metal compound selected from the group consisting of Ti, Zr, and Hf is 0.5 to 9.0%, the metal compound selected from the group consisting of Ca, Sr, and Ba The total content in terms of sulfate is 0.5 to 8.0%. In the annealing separator, the average particle diameter of the compound of the metal selected from the group consisting of Ca, Sr, and Ba is 12 μm or less, and the average particle diameter of the compound of the metal selected from the group consisting of Ca, Sr, and Ba is The ratio to the average particle diameter of the compound of the metal selected from the group consisting of Y, La, and Ce is 0.1 to 3.0, and the total content in terms of oxide of the compound of the metal selected from the group consisting of Y, La, and Ce, Ti, Zr, The total content of the metal compounds selected from the group consisting of Hf in terms of oxides is 2.0 to 12.5%. The ratio of the sum of the numbers of Y, La, and Ce atoms to the sum of the numbers of Ti, Zr, and Hf atoms contained in the annealing separator is 0.18 to 4.0.

[additive]

The additive contains Y, La, Ce compound, Ti, Zr, Hf compound, and Ca, Sr, Ba compound. The contents of Y, La, Ce compound, Ti, Zr, Hf compound and Ca, Sr, Ba compound are as follows.

[Compound of a metal selected from the group consisting of Y, La, and Ce]

Compounds of metals selected from the group consisting of Y, La, and Ce (referred to as Y, La, and Ce compounds) contain 0.8 to 8.0% in total in terms of oxides when the MgO content in the annealing separator is 100% by mass. do. Here, any one type of Y, La, Ce compound contained in the annealing separator is defined _{as M RE} , and the oxide content W _RE (mass %) _{of M RE in the annealing separator is as follows.}

W _RE = (M _RE addition amount (mass %))/( _{Molecular weight of M RE} ) × ((Molecular weight of Y ₂ O ₃ ) × ( _{number of Y atoms per M RE} 1 molecule/2) + (Molecular weight of _{La 2} O _{3 )} )×(Number of La atoms per molecule of _{M RE} /2)+(Molecular weight of _{CeO 2} )×(Number of Ce atoms per molecule of _{M RE))}

In addition, _{with respect to the M RE , the ratio x RE} of the sum of the number of Y, La, and Ce atoms to the number of Mg atoms included in the annealing separator is as follows.

x _RE = ((M _RE 1 be Y atoms per molecule) + (M _RE 1 number of atoms of La per molecule) + (M _RE 1 number of atoms of Ce per molecule)) × (the amount of M _RE (% by weight) Molecular weight of /M _RE )×(Molecular weight of MgO/100)

Therefore, in the annealing separator to which one or two or more Y, La, and Ce compounds are added, the total content of Y, La, and Ce compounds in terms of oxides when the MgO content is 100% in mass % C _{RE (hereinafter referred to as oxide-converted content C RE} of the Y, La, Ce compound _{) and the ratio X RE} of the total number of Y, La, and Ce atoms to the number of Mg atoms in the annealing separator (hereinafter, Y, The abundance ratio of La and Ce atoms ( _{referred to as X RE} ) is the sum _{of W RE and x RE} of each of the compound species of metals selected from the group consisting of Y, La and Ce contained in the annealing separator, respectively.

The Y, La, and Ce compounds are, for example, oxides or hydroxides, carbonates, sulfates, etc. which are partially or entirely converted to oxides in the drying treatment and finish annealing treatment described later. Y, La, Ce compounds inhibit the aggregation of the primary coating. Y, La, Ce compounds also function as oxygen emitting sources. Therefore, the growth of the root of the primary film formed by the finish annealing is accelerated, and the oxide of the film becomes dense. As a result, the adhesiveness with respect to the steel plate of a primary coating becomes high, and rust resistance improves. When the oxide-converted content C _RE is less than 0.8%, the above effect cannot be sufficiently obtained. On the other hand, when the oxide equivalent content C _RE exceeds 8.0%, the root of the primary coating develops excessively. In this case, since the root of the primary film inhibits the magnetic domain wall movement, the magnetic properties are lowered. When the oxide-converted content C _RE exceeds 8.0%, the MgO content in the annealing separator is lowered, so that the production of forsterite is suppressed. That is, the reactivity decreases. Therefore, the oxide equivalent content C _RE is 0.8 to 8.0%. The preferable lower limit of oxide conversion content C _RE is 1.0 %, More preferably, it is 2.0 %. The preferable upper limit of oxide conversion content C _RE is 6.0 %, More preferably, it is 4.5 %.

[Compound of a metal selected from the group consisting of Ti, Zr, and Hf]

A metal compound selected from the group consisting of Ti, Zr, and Hf (referred to as Ti, Zr, and Hf compounds) contains 0.5 to 9.0% in total in terms of oxides when the MgO content in the annealing separator is 100% by mass%. do. Here, any one type of Ti, Zr, and Hf compound contained in the annealing separator is defined _{as M G4} , and the oxide content W _G4 (mass %) _{of M G4 in the annealing separator is as follows.}

W _G4 = (M _G4 addition amount (mass %))/( _{Molecular weight of M G4} )×((Molecular weight of _{TiO 2} )×(number of Ti atoms per _{M G4 molecule)+(Molecular weight of ZrO 2} )×(M _G4 1 Zr atoms per molecule)+(Molecular weight of _{HfO 2} )×(Hf atoms per _{M G4 molecule))}

In addition, _{with respect to M G4 , the ratio x G4} of the sum of Ti, Zr, and Hf atoms to the number of Mg atoms included in the annealing separator is as follows.

x _G4 = ((M _G4 1 number of atoms of Ti per molecule) + (M _G4 1 number of atoms of Zr per molecule) + (M _G4 1 number of atoms of Hf per molecule)) × (addition amount (mass%) of M _G4 /M _{molecular weight of G4} )×(molecular weight of MgO/100)

Therefore, in the annealing separator to which one or two or more Ti, Zr, and Hf compounds are added, the total content C _{G4 in terms of oxides of Ti, Zr, and Hf compounds when the MgO content is 100% by mass% (hereinafter referred to as oxide-converted content C G4} of Ti, Zr, and Hf compounds), and the ratio of the sum of Ti, Zr, and Hf atoms to the number of Mg atoms in the annealing separator X _G4 (hereinafter, Ti, Zr , the abundance ratio of Hf atoms X _G4 ) is the sum _{of W G4 and x G4} of each compound of a metal selected from the group consisting of Ti, Zr, and Hf contained in the annealing separator, respectively.

The Ti, Zr, and Hf compounds are, for example, oxides and hydroxides, carbonates, sulfates, etc. which are partially or entirely converted to oxides in the drying treatment and finish annealing treatment described later. When Ti, Zr, and Hf compounds are contained in the annealing separator together with Y, La, and Ce compounds, they react with some of the Y, La, and Ce compounds during finish annealing to form complex oxides. When the complex oxide is formed, the oxygen releasing ability of the annealing separator can be increased compared to the case where the Y, La, and Ce compounds are contained alone. Therefore, by containing Ti, Zr, and Hf compounds instead of Y, La, and Ce compounds, the growth of the root of the primary coating is inhibited while suppressing the decrease in magnetic properties accompanying the excessive containing of Y, La, and Ce compounds. It can promote and enhance the adhesion of the primary coating to the steel sheet. The said effect is not fully acquired as oxide conversion content C _{G4 is less than 0.5 %.} On the other hand, when the oxide-converted content C _G4 exceeds 9.0%, the MgO content in the annealing separator is lowered, so that the production of forsterite is suppressed. That is, the reactivity decreases, and as a result of the decrease in the amount of the surface oxide, the rust resistance deteriorates. Moreover, when oxide conversion content C _G4 exceeds 9.0 %, a magnetic characteristic may fall. When the oxide-converted content C _G4 is 0.5 to 9.0%, the adhesion of the primary coating to the base steel sheet can be improved while suppressing a fall in rust resistance and a fall in magnetic properties.

The preferable lower limit of oxide conversion content C _G4 is 1.0 %, More preferably, it is 2.0 %. The preferable upper limit of oxide conversion content C _G4 is 8.0 %, More preferably, it is 7.5 %.

[Total content _{of oxide equivalent content C RE} of Y, La, Ce compound _{and oxide equivalent content C G4} of Ti, Zr, Hf compound]

_{The total content of the oxide equivalent content C RE} of the Y, La, and Ce compound _{and the oxide equivalent content C G4} of the Ti, Zr, and Hf compound is 2.0 to 12.5%. When the total content is less than 2.0%, the roots of the primary coating do not sufficiently grow, and the adhesiveness of the temporary coating to the steel sheet decreases. On the other hand, when the said total content exceeds 12.5 %, the root of a primary film develops excessively, and magnetic properties fall. _{Therefore, the total content of the oxide equivalent content C RE} of the Y, La, Ce compound _{and the oxide equivalent content C G4} of the Ti, Zr, and Hf compound is 2.0 to 12.5%. A preferable lower limit of this total content is 3.0 %, and a preferable upper limit is 11.0 %.

[Compound of a metal selected from the group consisting of Ca, Sr, and Ba]

The metal compound selected from the group consisting of Ca, Sr, and Ba (referred to as Ca, Sr, and Ba compounds) contains 0.5 to 8.0% in total in terms of sulfate when the MgO content in the annealing separator is 100% by mass%. do. Here, when any one Ca, Sr, Ba compound in the _{annealing separator is defined as MA AE} , when the MgO content in the annealing separator is 100%, the content W _{AE of MA AE} in terms of sulfate is as follows .

W _AE = M _AE molecular weight × (the mass% / M _AE (M _AE 1, the number of atoms of Ca per molecule) × (CaSO ₄ molecular weight) + (M _AE number of atoms of Sr per molecule) × (SrSO ₄ Molecular Weight) +(number of atoms of Ba per 1 molecule of _{MA AE} )×(Molecular weight _{of BaSO 4 ))}

Therefore, in the annealing separator to which one or two or more Ca, Sr, and Ba compounds are added, the total content of Ca, Sr, and Ba compounds in terms of sulfates when the MgO content is 100% by mass % C _AE (hereinafter referred to, Ca, Sr, Ba oxide in terms of the content of the compound C _AE) is the sum of W _G4.

Ca, Sr, and Ba compounds are, for example, sulfates, hydroxides, carbonates and the like. Since Ca, Sr, and Ba ions diffuse rapidly in the film, the addition of Ca, Sr, and Ba compounds increases the rate of formation of the film, and the film becomes dense and rust resistance is improved. If the content of sulfate in terms of _AE C is less than 0.5%, the above effect can not be obtained sufficiently. On the other hand, when sulfate conversion content _CAE exceeds 8.0 %, the root of a primary film develops excessively, and a magnetic characteristic may fall. In addition, when the sulfate-converted content _CAE exceeds 8.0%, the oxide inside the steel sheet becomes too dense, micro defects are generated in the film due to degassing from the steel sheet after the final annealing, and the rust resistance is deteriorated. . When the sulfate-converted content _CAE is 0.5 to 8.0%, the adhesion of the primary coating to the base steel sheet can be improved while suppressing a decrease in magnetic properties, and the rust resistance of the grain-oriented electrical steel sheet can be improved.

_{The average particle diameter PS AE} of the Ca, Sr, and Ba compounds is 12 μm or less. _{When the average particle diameter PS AE} of the Ca, Sr, and Ba compounds exceeds 12 μm, the film formation does not accelerate, and the film adhesion is improved by the effect of compound addition of the Y, La, Ce compound and the Ti, Zr, Hf compound. Even if it does, a film does not become dense and it is hard to improve rust resistance. Therefore, the average particle diameter PS _AE is 12 µm or less. A preferable upper limit of the average particle diameter PS _AE is 8 µm, more preferably 6 µm. The average particle diameter is not particularly limited with respect to the lower limit of the PS _AE, it is the industrial production phase, e.g., at least 0.01㎛.

The average particle diameter PS _RE measures the Y, La, Ce compound powder by a laser diffraction/scattering method based on JIS Z8825 (2013) using a laser diffraction/scattering particle size distribution analyzer. Thereby, it becomes possible to obtain the average particle diameter PS _RE. Similarly, the average particle diameter PS _AE is measured by the laser diffraction/scattering method based on JIS Z8825 (2013) using a laser diffraction/scattering particle size distribution analyzer for Ca, Sr, and Ba compound powder. . Thereby, it becomes possible to obtain the average particle diameter PS _AE.

As described above, since Ca, Sr, and Ba ions diffuse rapidly in the primary film, the rate of formation of the primary film is increased by the addition of Ca, Sr, and Ba compounds. In addition, by reducing the diameter of the Ca, Sr, and Ba compounds, the formation rate of the primary film is further increased. By controlling the particle size ratio of the Y, La, Ce compound and Ca, Sr, Ba compound having oxygen releasing ability to a specific range, the formation of the primary film is more accelerated than simply reducing the diameter of the Ca, Sr, Ba compound. , the size of oxide particles, which are each constituent unit of the primary film, becomes uniform and fine, and a dense film is obtained. As a result, the exposure of the steel sheet surface is reduced, and the rust resistance of the grain-oriented electrical steel sheet is improved. From that point of view, the ratio of the average particle diameter of the Ca, Sr, and Ba compounds to the average particle diameter of the Y, La, and Ce compounds (average particle diameter ratio RA _AE/RE ) is 0.1 to 3.0. When the average particle size ratio RA _AE/RE is less than 0.1, the oxygen releasing ability for the decomposition of Ca, Sr, and Ba compounds is insufficient, and the diffusion flow rate of Ca, Sr, and Ba into the film becomes small, and the above effect cannot be obtained. In addition, when the ratio of the average particle diameter of the Ca, Sr, and Ba compounds to the average particle diameter of the Y, La, and Ce compounds (average particle diameter ratio RA _AE/RE ) exceeds 3.0, the diffusion sites of Ca, Sr, and Ba Since it is limited, since the diffusion flow rate into the film of Ca, Sr, and Ba becomes small, the said effect cannot be acquired.

The average particle size ratio RA _AE/RE is calculated by the following method. _{The average particle diameter PS AE} is calculated|required by the measuring method similar to the average particle diameter PS _{RE mentioned above.} Using the obtained average particle diameters PS _RE and PS _{AE , the average particle diameter ratio RA AE/RE} is calculated|required by the following formula.

Average _{particle diameter ratio RA AE/RE} = Average particle diameter PS _AE / Average particle diameter PS _RE

[(Y+La+Ce)/(Ti, Zr, Hf) ratio in the number of atoms in the annealing separator]

_{The ratio (X RE} /X _G4 ) of the sum of the numbers of Y, La, and Ce atoms to the sum of the numbers of Ti, Zr, and Hf atoms contained in the annealing separator is 0.18 to 4.0. When X _RE /X _G4 is less than 0.18, during the finish annealing, Ti, Zr, and Hf which do not react with Y, La, and Ce atoms increase too much, so that the film does not become dense. Therefore, rust resistance deteriorates. On the other hand, _{even if X RE} /X _G4 exceeds 4.0, the growth of the film is not promoted, and the adhesion is lowered. When X _RE /X _G4 is 0.18 to 4.0, the adhesion of the primary coating to the steel sheet increases. A preferable lower limit of X _RE /X _G4 is 0.3, more preferably 0.5. A preferable upper limit of X _RE /X _G4 is 3.0, more preferably 2.0.

_{[N RE} , N _G4 , N _AE in annealing separator]

When adjusting the annealing separator, if the number density of particles in the raw material powder of rare earth element compounds such as Y, La, Ce, etc., metal compounds such as Ti, Zr, Hr, and additives such as Ca, Sr, Ba is insufficient, the primary A region where the development of the film is insufficient may occur, and adhesion and rust resistance may be deteriorated. In the raw material powder contained in the annealing separator, the number density of particles having a particle diameter of 0.1 μm or more of the metal compound selected from the group consisting of Y, La, and Ce N _RE , Ti, Zr, and Hf Particle diameter of the metal compound selected from the group consisting of Hf 0.1 _{The number density N AE} of particles having a particle diameter of 0.1 μm or more of a metal compound selected from the group consisting of number density N _G4 and Ca, Sr, and Ba of particles having a particle size of not less than μm is 2 billion particles/g or more, respectively. The particle diameter of these metal compounds is calculated|required as a volume-based equivalent sphere diameter, and it is calculated|required from the particle-size distribution based on the particle|grain number obtained by measuring raw material powder with a laser diffraction type particle size distribution measuring apparatus.

Here, the particle size distribution based on the number of particles refers to a particle size range in which an arbitrary value in the range of 0.1 to 0.15 µm is the minimum diameter and an arbitrary value in the range of 2000 to 4000 µm is the maximum diameter in a logarithmic scale such that the range is 30 or more. After dividing into equal widths in each section, the existence frequency (%) of the particles in each section is shown with respect to all particles. Here, the representative particle diameter D of each section is, using the upper limit D _MAX [μm] and the lower limit D _MIN [μm] of each section,

D=10^((LogD _MAX +LogD _MIN )/2)

saved as

In addition, the weight w [g] of the particles of each section in the particles of 100 raw powders is the abundance frequency f with respect to all particles, the representative particle diameter D [μm], and the specific gravity d [g/μm ³ ] of the metal compound is used. So,

w=f·d·(D^3·π)/6

saved as

Since the sum W [g] of w of all sections is the average weight of 100 raw material powder particles, the number of particles n [pieces/g] in 1 g of the metal compound powder is

n=100/W

saved as

_{When determining the number density N RE} of particles having a particle diameter of 0.1 μm or more of a metal compound selected from the group consisting of Y, La, and Ce, the number n of particles in 1 g of each metal compound powder in the raw material powder is calculated, and each metal Using the content c (%) in the slurry of the compound and the total C (%) of all the content c,

N _RE =Σ(n c/C)

saved as N _G4 and N _AE are similarly calculated|required.

If N _RE or N _G4 is less than 2 billion pieces/g, during the finish annealing, the root growth effect of the primary coating is biased, and a region where root growth is not sufficiently promoted occurs. As a result, not only the adhesion of the primary coating to the steel sheet is not sufficiently obtained, but also the diffusion path of the alkaline earth metal element cannot be secured, leading to deterioration of rust resistance. When N _RE and N _G4 are 2 billion pieces/g or more, the adhesiveness of a primary film becomes high. Y, La, Ce, Ti, Zr, Hf, etc. have an effect of releasing oxygen during finish annealing, and Y, La and Ce gently release oxygen from low temperature to high temperature. On the other hand, although Ti, Zr, and Hf can be considered to have a relatively short oxygen release period, they have the effect of increasing the oxygen release effect of Y, La, and Ce, and can continuously suppress the aggregation of the internal oxide layer necessary for the development of the film. I think. Therefore, it is thought that this interaction can be acquired effectively by making a number density high and raising the dispersion state in a separating agent layer.

If it is in the preferable range of _{RAAE/RE , and N RE} , N _G4 , N _AE is 2 billion pieces/g or more, the development of a film will become more remarkable and rust resistance will become favorable. The reason for this is that when the particle diameters of the Y, La, and Ce compounds and the Ca, Sr, and Ba compounds are matched to the same degree, when preparing a slurry, when X _RE /X _G4 is in the above-mentioned preferred range, the Ti, Zr, and Hf compounds are A region in which oxygen emission is enhanced and disposed in the vicinity of the Y, La, Ce compound can be secured without bias with respect to the plate surface, so that the diffusion path of the alkaline earth metal with fast diffusion is maintained even during constant temperature annealing, thereby making the film more uniform This is thought to be due to the promotion of development.

On the other hand, if it is outside the preferred range of _{RA AE/RE , or if N RE} , N _G4 , N _AE is insufficient (less than 2 billion cells/g), a region where the primary coating is insufficiently developed occurs. In this case, rust resistance falls.

[Manufacturing conditions of the final annealing process]

The finish annealing process is performed under the following conditions, for example. Prior to finish annealing, a drying treatment is performed. First, an annealing separator of an aqueous slurry is applied to the surface of the steel sheet. A steel sheet coated with an annealing separator on its surface is charged and held in a furnace maintained at 400 to 1000°C (drying treatment). Thereby, the annealing separator applied to the surface of the steel sheet is dried. The holding time is, for example, 10 to 90 seconds.

After drying the annealing separator, finish annealing is performed. In the finish annealing, the annealing temperature is set to 1150 to 1250°C, and the base steel sheet (cold rolled steel sheet) is cracked. The soaking time is, for example, 15 to 30 hours. The furnace atmosphere in the finish annealing is a well-known atmosphere.

In the grain-oriented electrical steel sheet produced by the above production process, the film forming the first containing Mg ₂ SiO ₄ as a major component. Further, the Al peak position D _Al is arranged in the range of 2.4 to 12.0 mu m from the surface of the primary film. Further, the Al oxide number density ND is 0.03 to 0.18/μm ² . Further, among the plurality of Al oxides in the observation region at the peak position of the Al emission intensity ^{, the ratio of the total cross-sectional area of a specific Al oxide having a cross-sectional area of 0.4 to 10.0 μm 2} to the total cross-sectional area of all Al oxides in the observation region (hereinafter , the specific Al oxide area ratio RA _AREA ) is 75.0% or more.

Further, each element of the chemical composition of the hot-rolled steel sheet is removed to some extent from the components in the steel by the decarburization annealing process and the finish annealing process. The composition change (and process) in the finish annealing process is sometimes called "purification (annealing)", and in addition to Sn, Sb, Bi, Te, and Pb utilized to control the crystal orientation, especially S functioning as an inhibitor , Al, N, etc. are largely removed. Therefore, compared with the chemical composition of the hot-rolled steel sheet, the element content in the chemical composition of the base steel sheet of the grain-oriented electrical steel sheet is lowered as described above. When the manufacturing method is performed using the hot-rolled steel sheet having the above-described chemical composition, a grain-oriented electrical steel sheet having a base steel sheet having the above chemical composition can be manufactured.

[Secondary film formation process]

In an example of the method for manufacturing a grain-oriented electrical steel sheet according to the present invention, the secondary film forming step may be further performed after the finish annealing step. In the secondary film forming step, an insulating coating agent mainly composed of colloidal silica and phosphate is applied to the surface of the grain-oriented electrical steel sheet after the temperature reduction of the finish annealing, and then baking is performed. Thereby, the secondary film which is a tension insulating film is formed on the primary film.

[Magnetic domain refining process]

The grain-oriented electrical steel sheet according to the present invention may further be subjected to a magnetic domain refining treatment step after the finish annealing step or the secondary film forming step. In the magnetic domain refining treatment step, the surface of the grain-oriented electrical steel sheet is irradiated with a laser beam having a magnetic domain refining effect, or a groove is formed on the surface. In this case, it is also possible to manufacture a grain-oriented electrical steel sheet having excellent magnetic properties.

Example

Hereinafter, the aspect of this invention is demonstrated concretely by an Example. These Examples are examples for confirming the effect of the present invention, and do not limit the present invention.

[Production of grain-oriented electrical steel sheet]

Molten steel of the chemical composition shown in Table 1 was manufactured with the vacuum melting furnace. Using the prepared molten steel, a slab was manufactured by a continuous casting method.

The slab was heated at 1350°C. Hot rolling was performed on the heated slab to prepare a hot rolled steel sheet having a sheet thickness of 2.3 mm. The chemical composition of the hot-rolled steel sheet was the same as that of the molten steel, as shown in Table 1.

The hot-rolled steel sheet was annealed, and then the hot-rolled steel sheet was pickled. The conditions of the annealing treatment for the hot-rolled steel sheet and the pickling conditions for the hot-rolled steel sheet were the same for all test numbers.

The hot-rolled steel sheet after pickling was cold-rolled, and the cold-rolled steel sheet which has a plate|board thickness of 0.22 mm was manufactured. In any test number, the cold rolling rate was 90.4 %.

The cold-rolled steel sheet was subjected to primary recrystallization annealing also serving as decarburization annealing. The annealing temperature in the primary recrystallization annealing was 750-950 degreeC in any test number, and the holding time at the annealing temperature was 2 minutes.

To the cold-rolled steel sheet after primary recrystallization annealing, an aqueous slurry was applied and dried, and an annealing separator was applied at a rate of ^{5 g/m 2 per side.} In addition, the aqueous slurry was adjusted by mixing an annealing separator (raw material powder) and industrial pure water in a mixing ratio of 1:5. The annealing separator contained MgO and the additives shown in Tables 2 and 3. _{In addition, the content C RE} (mass %) of the Y, La, Ce compound in the annealing separator shown in Tables 2 and 3 is Y in oxide conversion when MgO in the annealing separator is 100% by mass %, It means the total content of La and Ce compound (Oxide conversion content C _RE of Y, La, and Ce compound). Similarly, the Y, La, and Ce abundance _{ratios X RE} shown in Tables 2 and 3 mean the ratio of the total number of Y, La, and Ce atoms to the number of Mg atoms contained in the annealing separator. _{Similarly, the content C G4} (mass %) of the Ti, Zr, and Hf compounds in the annealing separator shown in Tables 2 and 3 is Ti in oxide conversion when MgO in the annealing separator is 100% by mass, It means the total content of Zr and Hf compound (Oxide conversion content C _G4 of Ti, Zr, and Hf compound). Similarly, Ti, Zr, and Hf abundance ratio X _G4 shown in Tables 2 and 3 means the ratio of the total number of Ti, Zr, and Hf atoms to the number of Mg atoms contained in the annealing separator. _{Similarly, the content CAE} (mass %) of Ca, Sr, and Ba compounds in the annealing separator shown in Tables 2 and 3 is Ca in sulfate conversion when MgO in the annealing separator is 100% by mass, The total content (Ca, Sr, and Ba compounds in terms of sulfate content CA _AE ) of the compounds of Sr and Ba is meant. Similarly, the Y, La, Ce number density N _RE shown in Tables 2 and 3 is 0.1 in the particle size of the metal compound raw material powder selected from the group consisting of Y, La, Ce in the annealing separator before adjusting to the aqueous slurry. It means the number density of particles of μm or more. Similarly, Ti, Zr, and Hf number density N _G4 shown in Tables 2 and 3 is a particle size of 0.1 in the metal compound raw material powder selected from the group consisting of Ti, Zr, and Hf in the annealing separator before adjusting to the aqueous slurry. It means the number density of particles of μm or more. Similarly, the Ca, Sr, and Ba number density N _AE shown in Tables 2 and 3 is a particle size of 0.1 in the metal compound raw material powder selected from the group consisting of Ca, Sr, and Ba in the annealing separator before adjusting to the aqueous slurry. It means the number density of particles of μm or more. In addition, a particle diameter is a sphere equivalent diameter on a volume basis.

_{The average particle diameter PS AE} (μm) in Tables 2 and 3 means the average particle diameter of the Ca, Sr, and Ba compounds measured by the above-mentioned measuring method. _{The average particle diameter PS RE} (μm) in Tables 2 and 3 means the average particle diameter of Y, La, and Ce compounds measured by the above-mentioned measuring method. _{RA AE/RE} in Tables 2 and 3 means the ratio of the average particle diameters of the Ca, Sr, and Ba compounds to the average particle diameters of the Y, La, and Ce compounds measured by the above-described measurement method.

With respect to the cold-rolled steel sheet to which the aqueous slurry was apply|coated on the surface, in any test number, the drying process was performed at 900 degreeC for 10 second, and the aqueous slurry was dried. After drying, a finish annealing treatment was performed. In the finish annealing treatment, in any test number, it was maintained at 1200°C for 20 hours. Through the above manufacturing process, a grain-oriented electrical steel sheet having a base steel sheet and a primary film was manufactured.

[Analysis of chemical composition of base steel sheet of grain-oriented electrical steel sheet]

With respect to the base steel sheets of the grain-oriented electrical steel sheets of Test Nos. 1 to 100, the chemical composition of the base steel sheets was determined by spark discharge emission spectrometry and atomic absorption spectrometry. The obtained chemical composition is shown in Table 4 and Table 5.

[Evaluation Test]

[Al peak position D _Al measurement test]

For the grain-oriented electrical steel sheets of each test number, the Al peak position D _Al was determined by the following measurement method. Specifically, the surface layer of the grain-oriented electrical steel sheet is subjected to elemental analysis using the GDS method, and elemental analysis is performed in a range (surface layer) of 100 μm in the depth direction from the surface of the grain-oriented electrical steel sheet, and at each depth position in the surface layer. Al contained was identified. The emission intensity of the identified Al was plotted in the depth direction from the surface. Based on the plotted graph of Al emission intensity, the Al peak position D _Al was determined. The calculated Al peak position D _Al is shown in Tables 6 and 7.

[Number Density ND Measurement Test of Al Oxide]

For the grain-oriented electrical steel sheet of each test number, the Al oxide number density ND (pieces/µm ² _{) at the Al peak position D Al} was obtained by the following method. Glow discharge was performed to Al peak position D _{Al with a glow discharge emission spectrometer.} Elemental analysis by an energy dispersive X-ray spectroscopy (EDS) is performed on an arbitrary 52 µm×39 µm region (observation region) among the discharge traces at the Al peak position D _{Al, and Al oxide in the observation region is} specified. Among the precipitates in the observation region, those containing Al and O were identified as Al oxides. The number of specified Al oxides was counted, and the Al oxide number density ND (pieces/µm ² ) was calculated by the following formula.

ND = number of specified Al oxides/area of observation area

The determined Al oxide number density ND is shown in Tables 6 and 7.

[Specific Al oxide area ratio RA _AREA measurement test]

The specific Al oxide area ratio RA _AREA was obtained by the following method. Glow discharge was performed to Al peak position D _{Al with a glow discharge emission spectrometer.} Elemental analysis by energy dispersive X-ray spectroscopy (EDS) is performed on an arbitrary 30 µm x 50 µm region (observation region) among the discharge traces at the Al peak position D _{Al, and Al oxide in the observation region is} specified. Specifically, with respect to the maximum intensity of the characteristic X-rays of O in the observation region, a region in which the intensity of the characteristic X-rays of O of 50% or more is analyzed was specified as an oxide. In the specified oxide region, with respect to the maximum intensity of the specific X-ray of Al, the region in which the intensity of the specific X-ray of Al of 30% or more is analyzed was specified as Al oxide. Based on the measurement results, a distribution map of Al oxide in the observation region was created.

In the prepared distribution map (observation region), the area of each Al oxide was calculated. Based on the calculation results, the Al oxide having an area of 0.4 to 10.0 µm ² was recognized as the specific Al oxide in the distribution diagram. The total cross-sectional area of a specific recognized Al oxide was obtained. Further, the total cross-sectional area of all Al oxides in the distribution diagram was obtained, and the specific Al oxide area ratio RA _AREA was obtained based on the following equation.

Specific Al oxide area ratio RA _AREA = Total cross-sectional area of specific Al oxides in observation area/Total cross-sectional area of all Al oxides in observation area×100

[Y, La, Ce, Ti, Zr, Hf, Ca, Sr, Ba measurement test in the primary film]

For the grain-oriented electrical steel sheet of each test number, Y, La, Ce content (mass %), Ti, Zr, Hf content (mass %), and Ca, Sr, Ba content (mass %) in the primary film by the following method was measured. Specifically, the grain-oriented electrical steel sheet was electrolyzed to separate the primary coating layer from the surface of the base steel sheet. Mg in the separated primary film was quantitatively analyzed by ICP-MS. The obtained quantitative value (mass%) of the product of the molecular weight of Mg ₂ SiO _4, by dividing the atomic weight of Mg, was determined the content of Mg ₂ SiO ₄ eq. Y, La, Ce, Ti, Zr, Hf, Ca, Sr, and Ba in the primary film were measured by the following method. The grain-oriented electrical steel sheet was electrolyzed to separate the primary coating layer from the surface of the base steel sheet. Y, La, Ce content (mass %), Ti, Zr, Hf content (mass %), and Ca, Sr, Ba content (mass %) in the separated primary film were obtained by quantitative analysis by ICP-MS. The Y, La, Ce content (mass %), Ti, Zr, Hf content (mass %), and Ca, Sr, Ba content (mass %) obtained by the measurement are shown in Table 6 and Table 7.

[Magnetic Characteristics Evaluation Test]

The magnetic properties of the grain-oriented electrical steel sheets of each test number were evaluated by the following method. Specifically, a sample having a length of 300 mm in a rolling direction and a width of 60 mm in the rolling direction was taken from the grain-oriented electrical steel sheet of each test number. A magnetic field of 800 A/m was applied to the sample to determine the magnetic flux density B8. Table 6 and Table 7 show the test results. When the magnetic flux density B8 was 1.92T or more, it was judged that the magnetic properties were excellent.

[Adhesiveness evaluation test]

The adhesiveness of the primary coating film of the grain-oriented electrical steel sheet of each test number was evaluated by the following method. Specifically, samples having a length of 60 mm in a rolling direction and a width of 15 mm were taken from the grain-oriented electrical steel sheet of each test number. The sample was subjected to a bending test with a curvature of 10 mm. The bending test was carried out using a bending resistance tester (manufactured by TP Kiken Co., Ltd.), installed on the sample so that the axial direction of the cylinder coincided with the width direction of the sample. The surface of the sample after the bending test was observed, and the total area of the area in which the primary film remained without peeling was calculated|required. The primary film residual ratio was calculated|required by the following formula.

Primary film residual ratio = Total area of the region where the primary film remains without peeling/Sample surface area × 100

Table 6 and Table 7 show the test results. When the primary coating residual ratio was 90% or more, it was judged that the primary coating film had excellent adhesion to the mother steel sheet.

[Rust resistance evaluation test]

The rust resistance of the coating film of the grain-oriented electrical steel sheet of each test number was evaluated by the following method. Specifically, a predetermined insulating film was applied to the grain-oriented electrical steel sheet of each test number, and was maintained at a temperature of 80°C and in a wet (RH 98%) atmosphere for 48 hours. The occurrence rate of red rust was calculated|required from the following formula.

The occurrence rate of red rust = total area of the area where red rust is confirmed / area of the test piece

Table 6 and Table 7 show the test results. A case in which no red rust occurred was indicated by "○", an incidence rate of less than 5% of red rust was indicated by "Δ", and a case in which the incidence rate of red rust exceeded 5% was indicated by "X". If red rust did not occur (that is, if "○" in Tables 6 and 7), it was judged that the rust resistance exerted by the temporary coating on the base steel sheet was excellent.

[Test result]

Table 6 and Table 7 show the test results. With reference to Tables 6 and 7, in Test Nos. 25 to 27, 35, 36, 40, 43, 44, 51 to 55, 59, 60, 69, 70, 76 to 78, the chemical composition of the base steel sheet was appropriate. . In addition, the manufacturing conditions, especially additives in the annealing separator, were also appropriate. Therefore, the Al peak position D _Al was in the range of 2.4 to 12.0 µm, and the Al oxide number density ND was in the range ^{of 0.03 to 0.18 pieces/µm 2 .} In addition, the specific Al oxide area ratio RA _AREA was 75.0% or more. In addition, the Ce content in the primary film was in the range of 0.001 to 8.0%, the Zr content was in the range of 0.0005 to 4.0%, and the Ca content was in the range of 0.0005 to 4.0%.

In particular, Test Nos. 26, 27, and 51 to 55 contain at least two or more compounds of a metal selected from the group consisting of Ti, Zr, and Hf. magnetic properties.

On the other hand, in Test Nos. 1, 2, 6 to 8, although the chemical composition was appropriate, the content C _RE of Y, La, Ce compounds in terms of oxide in the annealing separator was too low, and Ti in the annealing separator in terms of oxide, _{The content C G4} of the Zr and Hf compounds _{was too low, and the content C AE} of the sulfate converted Ca, Sr, and Ba compounds in the annealing separator was too low. Therefore, the Al peak position D _Al or Al oxide number density ND was too low. In addition, the specific Al oxide area ratio RA _AREA was less than 75.0%. As a result, the primary film residual ratio was less than 90 %, and adhesiveness was low. In addition, the rust resistance was low.

On the other hand, in Test Nos. 3 to 5, 9 to 19, 21, 22, 33, 34 and 38, although the chemical composition was appropriate, the content C _RE of Y, La, Ce compound in terms of oxide in the annealing separator was too low. As a result, in the grain-oriented electrical steel sheets of these test numbers, for this reason, the specific Al oxide area ratio RA _AREA was less than 75.0%, and the rust resistance was low.

In Test Nos. 23, 24, 57 and 58, although the chemical composition was appropriate, the sulfate equivalent content CA _AE in the annealing separator was too low. Therefore, the specific Al oxide area ratio RA _AREA was less than 75.0%, and the rust resistance was low.

In Test Nos. 28 and 61, although the chemical composition was appropriate, the sulfate equivalent content CA _AE in the annealing separator was too high. Therefore, the specific Al oxide area ratio RA _AREA was less than 75.0%, and the rust resistance was low.

In Test Nos. 29, 62, 79, 80 and 82, although the chemical composition was appropriate, the average particle diameter PS _AE of Ca, Sr, and Ba compounds in the annealing separator was too high. Therefore, the specific Al oxide area ratio RA _AREA was less than 75.0%, and the rust resistance was low.

In Test Nos. 30, 56 and 63, although the chemical composition was appropriate, the average particle size ratio RA _AE/RE in the annealing separator was too high. Therefore, the specific Al oxide area ratio RA _AREA was less than 75.0%, and the rust resistance was low.

In Test No. 31, although the chemical composition was appropriate, the average particle size ratio RA _AE/RE in the annealing separator was too low. Therefore, the RA _AREA was too low. As a result, the primary film residual ratio became less than 75 %, and rust resistance was low.

In Test Nos. 20, 32, 37, 42 and 48, although the chemical composition was appropriate, the content C _G4 of Ti, Zr, and Hf compounds in terms of oxide in the annealing separator was too low. Therefore, the Al peak position D _Al or Al oxide number density ND was too low. As a result, the primary film residual ratio became less than 90 %, and adhesiveness was low.

In Test Nos. 39, 47 and 75, although the chemical composition was appropriate, the content C _G4 of Ti, Zr, and Hf compounds in terms of oxide in the annealing separator was too high. As a result, the magnetic properties deteriorated. In addition, the specific Al oxide area ratio RA _AREA was less than 75.0%, and the rust resistance was low.

In Test No. 41, although the chemical composition was appropriate, the ratio of the sum of the numbers of Y, La, and Ce atoms to the sum of the numbers of Ti, Zr, and Hf atoms contained in the annealing separator was too high. Al oxide number density ND was too low. As a result, the primary film residual ratio became less than 90 %, and adhesiveness was low.

In Test No. 45, although the chemical composition was suitable, _{the total content of the oxide equivalent content C RE} and the oxide equivalent content C _4G of the Y, La, Ce compound in the annealing separator was too high. Therefore, the specific Al oxide area ratio RA _AREA was less than 75.0%, and the rust resistance was low.

In Test No. 46, although the chemical composition was appropriate, the oxide equivalent content C _RE of the Y, La, Ce compound in the annealing separator was too high. Therefore, the magnetic flux density B8 was less than 1.92T, and the magnetic properties were low.

In Test No. 49, although the chemical composition was appropriate, the ratio of the sum of the numbers of Y, La, and Ce atoms to the sum of the numbers of Ti, Zr, and Hf atoms contained in the annealing separator was too low. Therefore, the specific Al oxide area ratio RA _AREA was less than 75.0%, and the rust resistance was low.

In Test No. 50, although the chemical composition was appropriate, _{the total content of oxide equivalent content C RE} and oxide equivalent content C _{G4 in} the annealing separator was too low. Therefore, the Al peak position D _Al and the Al oxide number density ND were too low. As a result, the primary film residual ratio became less than 90 %, and adhesiveness was low.

In Test Nos. 64 to 68, 71 to 74, and 81, although the chemical composition was appropriate, the average particle diameter ratio RA _AE/RE in the annealing separator was too low. Therefore, the RA _AREA was too low. As a result, the primary film residual ratio became less than 75 %, and rust resistance was low.

In Test Nos. 83 to 88, the number density of particles in the raw material powder of the Y, La, and Ce compounds was too small. Therefore, the Al oxide number density ND was too low, and the specific Al oxide area ratio RA _AREA was less than 75.0 %. As a result, the primary film residual ratio became less than 90 %, adhesiveness was low, and corrosion resistance was low.

In Test Nos. 89 to 94, the number density of particles in the raw powder of the Ti, Zr, and Hf compounds was too small. Therefore, the Al peak position D _Al was too low, and the specific Al oxide area ratio RA _AREA was less than 75.0%. As a result, the primary film residual ratio became less than 90 %, adhesiveness was low, and corrosion resistance was low.

In Test Nos. 95 to 100, the number density of particles in the raw material powder of the Ca, Sr, and Ba compounds was too small. Therefore, the specific Al oxide area ratio RA _AREA was less than 75.0%. As a result, although the primary film residual ratio was 90 % or more, corrosion resistance was low.

As mentioned above, embodiment of this invention is described. However, the above-mentioned embodiment is only an illustration for implementing this invention. Therefore, this invention is not limited to the above-mentioned embodiment, The above-mentioned embodiment can be suitably changed and implemented within the range which does not deviate from the meaning.

Claims (5)

grain-oriented electrical steel sheet,
in mass %,
C: 0.005% or less;
Si: 2.5 to 4.5%,
Mn: 0.02 to 0.2%,
At least one element selected from the group consisting of S and Se: 0.005% or less in total;
sol. Al: 0.01% or less, and
N: 0.01% or less
A base steel sheet having a chemical composition containing Fe and impurities,
A primary film formed on the surface of the base steel sheet and _{containing Mg 2} SiO ₄ as a main component,
The peak position of the Al emission intensity obtained when elemental analysis by glow discharge emission spectrometry was performed from the surface of the primary film in the thickness direction of the grain-oriented electrical steel sheet was 2.4 from the surface of the primary film in the thickness direction disposed within the range of 12.0 μm,
It is an Al oxide at the peak position of the Al emission intensity, and the number density of the Al oxide of 0.2 µm or more is 0.03 to 0.18/µm ² in terms of an area-based equivalent circle diameter,
^{The total cross-sectional area of a specific Al oxide having a cross-sectional area of 0.4 to 10.0 µm 2} among a plurality of Al oxides in an observation region of 30 µm×50 µm at the peak position of the Al emission intensity is the total cross-sectional area of all Al oxides in the observation region. 75.0% or more of the cross-sectional area, grain-oriented electrical steel sheet. in mass %,
C: 0.1% or less;
Si: 2.5 to 4.5%,
Mn: 0.02 to 0.2%,
At least one element selected from the group consisting of S and Se: 0.005 to 0.07% in total,
sol. Al: 0.005 to 0.05% and
N: 0.001 to 0.030%
A step of producing a cold-rolled steel sheet by performing cold rolling at a cold rolling rate of 80% or more with respect to a hot-rolled steel sheet containing Fe and impurities, the remainder containing Fe and impurities;
performing decarburization annealing on the cold rolled steel sheet;
applying an aqueous slurry containing an annealing separator to the surface of the cold-rolled steel sheet after the decarburization annealing, and drying the aqueous slurry on the surface of the cold-rolled steel sheet in a furnace at 400 to 1000°C;
a step of performing finish annealing on the cold-rolled steel sheet after the aqueous slurry is dried;
The annealing separator,
MgO and
Y, La, and at least one compound selected from the group consisting of Ce,
At least one or more compounds of a metal selected from the group consisting of Ti, Zr, and Hf;
containing at least one or more compounds of a metal selected from the group consisting of Ca, Sr, and Ba;
When the MgO content in the annealing separator is 100% by mass, the total oxide content of the compound selected from the group consisting of Y, La, and Ce is 0.8 to 8.0%, and the Ti, Zr, Hf The total content in terms of oxide of the metal compound selected from the group consisting of is 0.5 to 9.0%, and the total content in terms of sulfate of the compound of the metal selected from the group consisting of Ca, Sr, and Ba is 0.5 to 8.0%,
The average particle diameter of the compound of the metal selected from the group consisting of Ca, Sr, and Ba is 12 μm or less,
The ratio of the average particle diameter of the compound of the metal selected from the group consisting of Ca, Sr, and Ba to the average particle diameter of the compound of the metal selected from the group consisting of Y, La, and Ce is 0.1 to 3.0,
The sum of the total content of the metal compound selected from the group consisting of Y, La, and Ce in terms of oxide and the total content of the compound of the metal selected from the group consisting of Ti, Zr, and Hf in terms of oxide is 2.0 to 12.5%,
A ratio of the total number of Y, La, and Ce atoms to the total number of Ti, Zr, and Hf atoms contained in the annealing separator is 0.18 to 4.0,
In addition, it is a particle of a metal compound selected from the group consisting of Y, La, Ce, and the number density of particles of 0.1 μm or more with a sphere equivalent diameter on a volume basis is 2 billion pieces/g or more,
In addition, it is a particle of a metal compound selected from the group consisting of Ti, Zr, and Hf, and the number density of particles of 0.1 μm or more in terms of volume-based equivalent sphere diameter is 2 billion pieces/g or more,
In addition, the particles of a metal compound selected from the group consisting of Ca, Sr, and Ba, wherein the number density of particles of 0.1 μm or more in terms of volume-based equivalent sphere diameter is 2 billion pieces/g or more. 3. The method of claim 2,
The chemical composition of the hot-rolled steel sheet is also, instead of a part of Fe,
A method for producing a grain-oriented electrical steel sheet, comprising 0.6% or less in total of at least one element selected from the group consisting of Cu, Sb and Sn. 4. The method of claim 2 or 3,
The chemical composition of the hot-rolled steel sheet is also, instead of a part of Fe,
A method for producing a grain-oriented electrical steel sheet, comprising 0.03% or less in total of at least one element selected from the group consisting of Bi, Te and Pb. It is an annealing separator used in the production of grain-oriented electrical steel sheet,
MgO and
Y, La, and at least one compound of a metal selected from the group consisting of Ce;
At least one or more compounds of a metal selected from the group consisting of Ti, Zr, and Hf;
containing at least one compound of a metal selected from the group consisting of Ca, Sr, and Ba;
When the MgO content in the annealing separator is 100% by mass, the total oxide content of the compound selected from the group consisting of Y, La, and Ce is 0.8 to 8.0%, and the Ti, Zr, Hf The total content in terms of oxide of the metal compound selected from the group consisting of is 0.5 to 9.0%, and the total content in terms of sulfate of the compound of the metal selected from the group consisting of Ca, Sr, and Ba is 0.5 to 8.0%,
The average particle diameter of the compound of the metal selected from the group consisting of Ca, Sr, and Ba is 12 μm or less,
The ratio of the average particle diameter of the compound of the metal selected from the group consisting of Ca, Sr, and Ba to the average particle diameter of the compound of the metal selected from the group consisting of Y, La, and Ce is 0.1 to 3.0,
The sum of the total content of the metal compound selected from the group consisting of Y, La, and Ce in terms of oxide and the total content of the compound of the metal selected from the group consisting of Ti, Zr, and Hf in terms of oxide is 2.0 to 12.5%,
A ratio of the total number of Y, La, and Ce atoms to the total number of Ti, Zr, and Hf atoms contained in the annealing separator is 0.18 to 4.0,
In addition, it is a particle of a metal compound selected from the group consisting of Y, La, Ce, and the number density of particles of 0.1 μm or more in terms of volume-based equivalent sphere diameter is 2 billion pieces/g or more,
In addition, it is a particle of a metal compound selected from the group consisting of Ti, Zr, and Hf, and the number density of particles of 0.1 μm or more in terms of volume-based equivalent sphere diameter is 2 billion pieces/g or more,
In addition, the particles of the metal compound selected from the group consisting of Ca, Sr, and Ba, and the number density of particles of 0.1 μm or more in terms of volume-based equivalent sphere diameter is 2 billion pieces/g or more, an annealing separator.